Working with Northeastern United States lobster harvesters to develop acoustic trap retrieval in place of buoys and persistent vertical lines to reduce whale entanglements

Abstract

Vertical buoy lines (VBLs) between surface markers and bottom fishing gear frequently entangle large whales. These lethal and sublethal entanglements inhibit North Atlantic right whale (Eubalaena glacialis) recovery. Consequently, the use of persistent VBLs in situations of high entanglement risk off the east coasts of the USA and Canada is periodically prohibited. On demand, acoustic recovery systems make it possible to remove persistent VBLs, reducing entanglement risk, and potentially allowing fisheries to operate in such areas. To address concerns about performance, reliability, and safety, we evaluated numerous on-demand systems under normal fishing conditions. In 2020, conservationists, scientists, engineers, and lobster harvesters designed an experiment to trial on-demand systems in the New England offshore fisheries, using an open and honest dialogue while maintaining the confidentiality of data such as fishing locations. Between 2020 and 2023, 38 captains and their crews completed 5798 hauls using 431 on-demand units representing 10 different prototypes from multiple manufacturers. The geographic area expanded from limited offshore areas in 2020 to inshore, nearshore, and offshore waters in four different lobster management areas in 2022 and 2023. Trawl lengths ranged from 1 to 100 traps per trawl. Recovery success increased from 64% to 90% of hauls through the trials, although challenges remain, especially when fishing in deep waters or high current and tide locales. A parallel study is underway in Canada. The ability to ensure sustainable fisheries while significantly reducing entanglement risk is becoming a reality, with snow crabs and lobsters being sold in Canada and lobsters and Jonah crabs in the USA that were caught using experimental fishing permits and on-demand systems primarily in areas where persistent VBLs are seasonally prohibited for whale conservation.

on demand, ropeless, trials, gear conflict, marine mammal entrapment

Introduction

Lobster and crab harvesters typically deploy baited traps to the seafloor. Commercial fishing permits require the traps to have at least one vertical line from the traps to surface buoys. These vertical buoy lines (VBLs) enable trap retrieval for harvesting the catch and adding bait to the trap before it is deployed. Each buoy carries a permit number and marks the location of the gear. Single traps can each have a VBL or be deployed in groups (commonly called trawls in the NE USA, and not to be confused with mobile trawl gear) of ∼50 and occasionally more, with a groundline between each trap, and a VBL attached to each end of the trawl. Persistent VBLs present a serious risk of large whale entanglement (Johnson et al. 2005). Despite decades of risk reduction efforts directed at modifying fishing practices to reduce entanglement risk (Pace et al. 2021), the rate and impact of entanglements on large whales have escalated, affecting individual survival (Sharp et al. 2019), reproductive success (Knowlton et al. 2022, Reed et al. 2024), and, in the case of critically endangered North Atlantic right whales (Eubalaena glacialis), premature mortality (Breed et al. 2024) and a trajectory toward species extinction (Runge et al. 2023). Areas where the use of persistent VBLs is seasonally prohibited have been a primary tool to significantly reduce entanglement risk but come at a cost to economically and culturally valued fishing communities.

As the reduction of entanglements became essential for preventing the extinction of this species and closures were broadened to try and support that goal, the use of technology to achieve this has come to the forefront. Acoustic releases have been used for the recovery of bottom gear for science, industry, and defence sectors since at least the early 1960s (Heinmiller 1968). Their use as a whale entanglement avoidance strategy was considered in 1979 (by Jon Lein, personal communication to M. Moore), and perhaps before then by others. Research into its use as a fishing technology began in 1998 (DeAlteris 1999) and was recommended unanimously by the US Atlantic Large Whale Take Reduction Team for consideration as an experimental fishery in the Great South Channel off Nantucket, USA (ALWTRT 2010). The DeAlteris (1999) study considered operational requirements of the American lobster (Homarus americanus) fishery and available acoustic releases and then designed and iterated two systems. The final product was operational in up to a water depth of 200 m and functioned in 39/40 trials. The one failure was an operator error. The project then stalled as the necessity of floating markers to reduce conflicts with other gear (including other traps) made it impossible to find a regulatory path, including enforcement considerations, to allow traps to be set without VBLs and surface markers (ALWTRT 2010). Those markers are the means for avoidance of gear conflicts within the trap fisheries and with mobile fisheries such as bottom trawling for fish and shellfish.

After multiple right whale mortalities in 2017, a North Atlantic Right Whale Unusual Mortality Event (UME) was declared (NOAA 2024a). Given that at least 20 individual right whales were killed or badly injured because of entanglements in 2017, renewed interest in the concept of setting bottom traps without VBLs developed (Baumgartner et al. 2018), yet this required considerable efforts among scientists, engineers, harvesters, and manufacturers to translate the existing technology to be suitable for fishing activities via trials. Surface controlled acoustic triggers were further considered by Myers et al. (2019) and developed for releasing bottom-stowed buoyant bagged or spooled line, or air from a tank into inflatable lift bags as shown in Figs 1 and 2. The Ropeless Consortium (ropeless.org) was founded in 2018 to provide an annual international forum to discuss an approach for reducing entanglement risk by removing persistent VBLs from fishing bottom set gear. The goal was to find a pathway enabling commercial fishing in areas otherwise prohibited to fishing with VBLs for whale conservation purposes. At that time, the approach was referred to as “ropeless fishing,” referring to the lack of persistent line in the water column. However, given the continued use of groundline between traps in a trawl, and that some systems use bottom-stowed line for retrieval, the more accurate term “on-demand gear (ODG)” has been adopted by many. Other synonyms include buoyless and pop-up fishing. The concept was aired in this journal in 2019 (Moore 2019). The Ropeless Consortium has retained the ropeless moniker, as it presents the goal of whales without rope. See also this video (https://youtu.be/fhWGGeZenuU) summarizing the value of on-demand trap retrieval (Whale Dolphin Conservation 2024).

Figure 1.

Traditional and ODG systems for trap retrieval. Far left: Image of traditional VBLs that pose an entanglement risk. Right: Three different types of ODG systems that significantly reduce the probability of entanglement.

Figure 2.

Examples of ODG trap systems under trial. 1, 2, 4, and 6 have buoyant bottom-stowed ropes in a bag, cage, or spool and 3 and 5 use inflatable bags. Brand names: 1. Desert Star, 2. Sub Sea Sonics, 3. SMELTS, 4. Fiobuoy, 5. Ropeless Systems, and 6. EdgeTech. See Table 1 for these and other ODG brands used in trial.

In 2020, a group of US-based scientists, fishery managers, and conservationists met to evaluate the necessary permitting processes and data protocols required to trial on-demand fishing under normal fishing conditions. The result was the trials described here to evaluate and facilitate the development of effective systems to enable trap fishing in the American lobster fishery in areas of the US NE Continental Shelf, where the use of persistent VBLs is seasonally prohibited to reduce large whale entanglement risk. To do so required enhanced communication and trust among a diverse set of stakeholder groups, including gear manufacturers, harvesters, engineers, scientists, managers, and conservationists. The trials involved evaluating ODG systems and facilitating communication between harvesters and gear developers to improve the safety and efficiency of the gear in challenging oceanographic conditions. Operational issues were iteratively resolved while conducting targeted and systematic data collection. The work focused on the efficacy of the gear recovery solutions to replace persistent VBLs. The objective was primarily a qualitative familiarization of individual harvesters with the gear, enabling feedback to fishery managers and gear manufacturers, as opposed to a rigorous quantitative comparison of the operating characteristics of each gear brand. In essence, the study asked the following questions. What worked? What needed fixing?

Materials and methods

ODG library

A collection of 10 different ODG systems, contributed by the US Federal Government, nongovernmental organizations (NGOs), and manufacturers, was established as a “lending library” in Woods Hole, MA, USA, at the Northeast Fisheries Science Center (NEFSC), National Marine Fisheries Service (NMFS), and National Oceanographic Atmospheric Administration (NOAA) (see NEFSC 2022; Table 1; Figs 2–3). In addition to ODG units and acoustic releases, the gear library includes other essential equipment for gear deployment, retrieval, and evaluation, including, but not limited to, tablets for release activation and gear tracking, application software, cameras, tilt sensors, cellular signal boosters, light strobes, Blue Ocean Gear Smart Buoys (https://www.blueoceangear.com/), through-hull transducers, Starlink satellite internet hardware (https://www.starlink.com/), and satellite phones. Qualified participants were provided access to necessary gear at no cost. The first three to four participants were approached by the Gear Research Team to test the gear, but as word spread about the program, harvesters began to approach the team. The bar to qualify was a clean and active permit (i.e. no unresolved violations), and a permit check directly with the appropriate enforcement agencies. The gear comprised a blend of available brands. Equipment procurement was driven by availability and willingness of harvesters to use a particular brand, given prior involvement and other constraints. Thus, this was a development and discovery project, as opposed to a fully controlled scientific experiment.

Figure 3.

Number of acoustic release units available in each year, from each manufacturer. Dual manufacturers indicated as follows: recovery system/acoustic release. The predominance of EdgeTech gear resulted from early graduation through the three-phase process (described in the section “Gear trials”) and its manufacturing capacity as an established underwater acoustic technology company. The fishing industry collaborators showed a preference for EdgeTech systems early in the project due to their adaptation of proven acoustic release technology to familiar trap materials with the direct input of harvesters (Fig. 2). The units were available as a complete system that accomplished release controls and gear location marking/sharing (Trap Tracker). It was also a brand, at a mid-price point, that was available in the quantities and delivery times required by the project design.

Table 1.

Quantity of each brand of ODG in trials (as of 15 February 2024)

Brand	Total	Trigger	Mechanism	Source
Ashored	15	Acoustic	Trap-stowed line	https://ashored.ca/
Desert Star	7	Acoustic	Bag-stowed line	https://www.desertstar.com/
EdgeTech	296	Acoustic	Trap-stowed line	https://www.edgetech.com/
Fio Marine	3	Acoustic	Spool	https://fiomarine.com/
Lobster Lift	2	Acoustic	Lift bag	https://conservationx.com/project/id/225/lobsterlift
Ropeless Systems	5	Acoustic	Lift bag	https://www.ropeless.us/
SMELTS	56	Acoustic	Lift bag	https://www.smelts.org/
Sub Sea Sonics	27	Timer	Bottom-stowed line	https://www.subseasonics.com/
Sub Sea Sonics	18	Acoustic	Bottom-stowed line	https://www.subseasonics.com/
WHOI On-Call	2	Acoustic	Spool	https://www.whoi.edu/
Total	431

Stipends

To enable the study outside of closed areas, participating harvesters were provided with stipends in recognition of the additional time spent deploying and recovering ODG, and the collection of data on the performance of the systems. These stipends were funded by NOAA Fisheries, with funds disbursed by the Atlantic States Marine Fisheries Commission for participation in gear trials. Trial participants were required to collect and provide completed datasheets and provide feedback on gear performance, which was shared with the respective manufacturers. Where possible, timely gear modifications and adjustments were made by manufacturers in response, and gear was then redeployed for further evaluation.

Data collection

Each harvester was asked to record location, water depth, environmental conditions at setting and hauling, and retrieval times for each haul. In addition, information was collected on best practices for rigging and fishing the gear, problems encountered with gear deployment and retrieval, evaluation of electronic marking methods to avoid gear conflict, gear detection and activation ranges, suitability for inspection of gear by enforcement agencies, costs, safety, rough weather performance, movement in storms, ability to recover lost ODG, performance of hull-mounted transducers, capacity to collect oceanographic data using ODG, and ways to improve training and education programs. Given the absence of dedicated data collectors on each vessel, data collection was limited to the above parameters. Data were not always quantitative. Every harvester was given data sheets with space to fill in these fields, and there were spots for any additional notes/descriptions of certain scenarios. Other information may have come from having a conversation with the fisherman after that haul to further understand the situation.

Gear trials

Trials were divided into three phases. During Phase 1, harvesters were trained to be comfortable with system rigging and operation. In Phase 2, commercial fishing was conducted in a “hybrid trawl” format with an on-demand unit on one end of a trawl and a VBL on the other end. This allowed for the recovery of gear with the VBL if the on-demand unit failed to surface for any reason. Finally, a subset of experienced participants progressed to Phase 3, testing fully ODG (no VBLs) in areas and seasons prohibited to lobster fishing with persistent VBLs. A successful deployment was defined as an ability to electronically mark and relocate gear, release units off the seafloor using an acoustic signal, and safely and efficiently retrieve units after their release. In cases where the gear was not deployed and retrieved as intended, an evaluation of the cause of the issue was conducted.

Unsuccessful hauls were categorized as follows:

• Acoustic: The acoustic signal was interrupted when activated (e.g. transducer malfunction).

• Mechanical: A mechanical aspect of the system was interrupted when activated (e.g. rope snarls, damage due to elements).

• Technological: A technology aspect of the system interrupted a successful haul (e.g. dead batteries in tablet/deck box, Bluetooth connectivity, and/or software application issues).

• Operational: Recovery was interrupted because of a user error (e.g. incorrect rigging, incorrect selections on the user interface, failing to bring the tablet, etc.).

• Unknown: It was unknown why the system did not function as intended.

• Damage: There was physical damage to gear, preventing it from operating as intended (e.g. bent lid, broken transducer, or leaky bag)

• Environmental: The gear may have worked as intended, but due to environmental circumstances (e.g. dark, fog, tide, and currents), it was not retrieved successfully.

• Mix: A mix of interrupted operations occurred.

• Did not recover: It indicates that the on-demand system was not recovered at the initial time the haul was attempted. However, several systems were able to be recovered later.

Results

Harvesters were exempted from using VBLs within the lobster management areas (LMAs), and four restricted areas were closed to VBLs (NOAA 2021), all shown in Fig. 4. More specific location data are withheld out of respect for the privacy of individual harvesters.

Figure 4.

LMAs and seasonal vertical line restricted areas pertaining to the acoustic gear retrieval trials. Table 2 gives details of deployments. Gear has been tested in LMAs 1, 2, 2/3 overlap, 3, and 5 (south of New York—not shown). Also shown are the four seasonal vertical line restricted areas closed to trap fishing with vertical buoy lines but open for permitted (exempted) on-demand fishing for the dates shown in the legend (NOAA 2021).

Table 2 lists the number of vessels involved in 2020, 2021, 2022, and 2023. Additionally, in 2023, 12 trained harvesters, exempted from the legal requirement to use VBLs, by using on-demand systems successfully conducted two fisheries in areas where, for whale conservation, persistent VBLs were prohibited (Fig. 4) and listed in Table 2. The trials grew in both nearshore and offshore areas each year, as ODG availability increased, new manufacturers came online, and an increased number of harvesters were motivated to try the technology.

Table 2.

Number of boats by length in trials for each year in LMAs and restricted areas shown in Fig. 4

Nature	Year	Number of vessels with length <15.24 m	Number of vessels with length >15.24 m	Total boats	Home port state	Total hauls
Trial	2020	0	3	3	MA, RI	79
Trial	2021	8	2	10	ME, MA, RI	623
Trial	2022	19	3	22	ME, MA, RI	1851
Trial	2023	27	3	30	ME, MA, RI, MD	2715
Closure	2023 MA RA	5	1	6	MA	332
Closure	2023 SI RA	5	1	6	RI	209

Data from restricted areas (RA—persistent VBLs prohibited) are a subset of the 2023 overall trial numbers. MA, Massachusetts; RI, Rhode Island; SI, South Island; ME, Maine; MD, Maryland. Trawl lengths ranged from 1 to 100 traps. Set depths up to 411.5 m.

The number of hauls and success rates of ODG hauls for each of the 4 years of the study are shown in Table 3, and the reasons for unsuccessful hauls are given in Table 4.

Discussion

In this series of trials over a 4-year period, operational success and advances for ODG were enabled by the study (Fig. 4). The systems have costs and benefits and are still being further developed and enhanced. Most importantly, in the absence of traditional surface buoy markers to locate bottom gear, it is important that on-demand harvesters can see the location of not only their own gear but also gear owned by others, which will often be different brands. Thus, gear location reporting must be interoperable between brands. Additionally, other bottom fisheries also need to know all bottom gear locations wherever they fish. A recent workshop advanced this issue (NEFSC 2023).

Hauling success

Hauling success was notably better after the first year of the study when COVID restrictions limited in-person and onboard gear use training. On-demand operations became more efficient as fishing crew’s experience with systems increased with time (Fig. 5 and Table 3). Overall success rates improved but remained relatively consistent in subsequent years (83%–88%), which was likely due to new participants and new or modified gear types being tested each year. However, the highest success rate (90%) was documented in the experimental fishery where most experienced harvesters used a subset of ODG types in areas where persistent VBLs are prohibited. The unsuccessful hauls were retrieved by hauling the VBL at the other end of the trawl if it was a hybrid, or by grappling if both ends were acoustic in an exempted restricted area trial.

Figure 5.

Gear marking in the absence of surface markers attached to vertical buoy lines requires virtual gear marking. For low-gear-density areas, a GPS position for each end of the trawl of traps may be enough when recorded and shared via the cloud. For higher gear densities, the positions of the on-demand units must be acoustically shared and updated in real time. Virtual gear marking requires interoperable position reporting to be communicated between different brands of retrieval and data display systems.

Table 3.

A breakdown of the number of ODG hauls and success rates for each of the 4 years of the study

Year	2020	2021	2022	2023	2023 restricted areasa
# Blank haulsb	9	0	90	84	31
# Hauled alt wayc	0	0	0	3	0
Total # hauls excludedd	9	0	90	87	31
Total # unsuccessful hauls	29	94	206	393	57
Total # successful hauls	50	529	1645	2322	484
Total # hauls	79	623	1851	2715	541
Percentage of successful hauls	63.3	84.9	88.9	85.9	89.5
Percentage of unsuccessful hauls	36.7	15.1	11.13	14.5	10.54

Success rates improved substantially after the first year. The reasons behind the unsuccessful hauls shown here are detailed in Table 4.

a

Restricted areas (persistent VBLs prohibited) are a subset of the 2023 total.

b

Blank hauls are hauls that were not recorded by harvesters on their datasheets.

c

The number of hauls where the harvesters hauled an alternative way (e.g. hauled the VBL at the other end of the trawl due to weather, wind, or convenience) without attempting to trigger the on-demand system. Since the release of the on-demand system was not attempted, the haul cannot be determined successful or unsuccessful.

d

The total number of hauls excluded is the sum of the number of blank hauls and the number of hauls that were hauled an alternative way. These data were excluded from the total number of hauls, and the calculated percentage of successful hauls due to the lack of information.

Gear development

As seen in Table 4, mechanical, technological, and operational issues were the primary reasons for hauling failures. Most of the mechanical issues were line containment related, which resulted in snarls preventing a standard recovery. While some best management practices have been identified for pop-up style systems (line packing techniques and line type), this is an area where significant improvement is achievable with more data, underwater video, and experimental designs. Common technological issues included discharged batteries in either deck boxes or underwater units and user issues with tablet or application functions (Bluetooth connectivity, subscription renewals, password issues, and tablet or application updates). Common operational issues included incorrect rigging by a crew member, not enough air pressure (for lift bag systems only), not dunking the transducer deep enough in the water, and mistakenly selecting the incorrect unit to haul on the user interface, among others. The manufacturers have been included in the details of the issues, and it is likely that improved battery materials, streamlined user interfaces, and more individual industry experience using such technologies will result in improved results.

Table 4.

Reasons for unsuccessful hauls of ODG compared between calendar years—see the “Materials and methods” section for category definitions

Year	2020		2021		2022		2023		2023 restricted areasa
Acoustic	2	4.0%	3	3.2%	5	2.4%	38	9.7%	2	3.5%
Mechanical	17	34.0%	50	53.2%	88	42.7%	115	29.3%	29	50.9%
Technological	2	4.0%	9	9.6%	7	3.4%	60	15.3%	13	22.8%
Operational	1	2.0%	8	8.5%	14	6.8%	41	10.4%	2	3.5%
Unknownb	3	6.0%	16	17.0%	74	35.9%	81	20.6%	6	10.5%
Damage	2	4.0%	1	1.1%	7	3.4%	16	4.1%	1	1.8%
Environmental	0	0.0%	2	2.1%	5	2.4%	23	5.9%	0	0.0%
Mix	2	4.0%	5	5.3%	5	2.4%	13	3.1%	2	3.5%
Did not recoverc	0	0.0%	0	0.0%	1	0.5%	6	1.5%	2	3.5%
Total number of unsuccessful hauls	29		94		206		393		57

The numbers and percentages are in relation to the total number of unsuccessful hauls in the given calendar year. Total haul record (closed and open areas) excluding the times that gear was set without any further data submitted: 9 in 2020, 90 in 2022, 76 in 2023, and 32 in 2023 restricted area.

a

Restricted areas (persistent VBLs prohibited) are a subset of the 2023 total.

b

Unknown hauls is a category of unsuccessful hauls in which the cause of failure could not be determined.

c

Gear not recovered at initial attempt of hauling can be attributed to parting of connecting lines and assumed gear conflicts with mobile gears.

Harvesters using the gear have significantly contributed to the improvement of gear design and operability. As a result of their input and resulting design improvements, a notable reduction in mechanical problems was documented over the study period. Ongoing issues to resolve include locating the units once at the surface, at night or in the fog or in high seas, as the gear profile is low in most cases and does not include highfliers (vertical poles with flags) or detection by using radar reflectors. In terms of detecting surfaced ODG at night, in the fog, or in high seas, inflated SMELTS bags can be detected by radar, but there is a general need for better detection and recovery. Inflatable bags may be the best option for high-current areas such as eastern Maine, providing a larger time window to retrieve gear pulled under by strong tides. Strobe lights, reflector tape, and other solutions are being tested. Further testing will determine whether systems are viable in extreme currents (through hauling at slack water), water depth, or temperatures, or whether gear use limitations exist. The issue of gear conflict is discussed below.

Advances

On-demand fishing systems have been available for commercial use since 2012 (Desert Star 2025). This 4-year trial of multiple brands of ODG enabled a significant advance toward a viable alternative to complete closure of economically important areas to fishing to reduce entanglement risk. It coincided with, and enabled, one of the first substantive efforts to develop and test multiple on-demand systems in a commercial fishery. ODG can replace the use of traditional static VBLs and surface markers for recovery and detection of bottom traps. The most tangible result from this trial in the NE United States was commercial fishing with ODG in areas closed to the use of persistent VBLs, enabled by permits that allowed this. Similar trials were also underway in Canada, by the Acadian Crabbers Association, the Fédération Régionale Acadienne des Pêcheurs Professionnels (FRAPP) located in northern New Brunswick, the Canadian Centre for Fisheries Innovation [CCFI—(Hutchings 2022)], and the Canadian Wildlife Federation (CWF). CWF estimated that 454 tonnes (1000 000 lbs) of Canadian snow crab have been commercially harvested in two areas of the Gulf of St. Lawrence since 2022, with ODG in areas where traditional gear was prohibited (CWF https://www.cwf-fcf.org/, personal communication by email dated 28 May 2024). The experimental fisheries described in Tables 2 and 3 were one of the first commercial applications of on-demand technology in US waters. The willingness of both the US and Canadian governments to establish whale conservation areas open to ODG was significantly impacted by the demonstrated utility of the available gear in these trials, and parallel work in Canada by the Canadian Wildlife Federation and others. A major reason for this development was the close interaction between interested harvesters, federal gear scientists, NGOs, and gear manufacturers. ODG systems have also been used in other fisheries, including the US southeast and west coasts, Scotland, South Africa, and Australia.

Benefits

The most notable benefit of ODG is access to valuable fishing grounds where persistent VBL use is prohibited. This benefit is best described by the video “On Demand Technology: A Fisherman’s Story” at https://www.youtube.com/watch?v=v0j44FRTTJw. Additionally, the gear trial has documented ancillary benefits, including limited gear movement in storms because of the absence of persistent VBLs and surface buoys and their frontal drag, reducing gear loss. ODG loss was limited to 9/431 (2.1%) units in this 4-year study, which involved 38 different vessels and >5798 hauls. While the comparison between the loss of a retrieval device and a trap is not equivalent (trap loss can be between 1 and 50 or more per trawl, whereas on-demand unit loss is only ever one or at most two units per trawl), traditional American lobster traps set with VBLs undergo 5% to 30% annual losses (Smolowitz 1978, (Breen 1990). Loss can be attributed to groundlines and gangions parting, vessel and whale interactions, and conflicts with mobile gear or other fixed gears. When bottom-set gear movement has occurred, either by storms or being accidentally carried or towed by other fishing vessels, ODG has been easier to relocate than traditional gear. In at least one case, a harvester was able to relocate gear miles from where it was set by setting up a search pattern and using the transponder to bring the gear to the surface. Another benefit is that gear location marked on a digital device is not impacted by poor visibility and/or a high sea state. Additionally, when areas are closed to VBLs for whale conservation purposes, ODG can continue to be used and does not incur a removal cost. These benefits would add to the use of sinking groundlines by some trap fisheries, which has minimized residual groundline entanglement risk as summarized by Calderan et al. (2024).

Costs

There have been three analyses of the estimated costs of using ODG with variable results (Alkire 2022, Conservation Law Foundation 2023, Oppenheim et al. 2023). As on-demand systems remain in developmental and research stages, it is likely that costs will remain high with current costs averaging ∼US$4000 per release unit (one or two units per trawl of traps), US$4500 for one control (deck) box per vessel, US$4500 for an optional through-hull transducer (not including installation), and US$300 for tablet and software costs. However, some units in trial are now retailing for <US$1000. It is expected that costs will decrease with the redesign of releases for high-volume, low-cost manufacturing, volume production, and competition. Costs for cellular or satellite communications will also be incurred, although increasingly satellite internet is becoming more affordable for offshore vessels. In terms of added cost for longer hauling times, we attempted to have harvesters record time taken to haul using ODG, but variations between data recording methods on different vessels, gear upgrades, and transducer types made an analysis of the data unmeaningful. More data on this topic are being collected on a subset of trips using electronic video recording and data recording science staff aboard vessels for future analysis. Such data will be helpful, but even if there remains an increase in hauling time using on-demand as opposed to persistent VBLs, such a cost could be acceptable given the legal mandates for conservation and sustainability of both the fisheries and endangered species. Furthermore, given that ODG can allow for access in areas/times otherwise closed, the germane comparison is between not fishing and, potentially, slower fishing rather than between VBL and on-demand modalities. In Canada, the snow crab harvesters in the southern Gulf of St. Lawrence that formerly used single traps now use 10-pot trawls (some higher) when fishing with ODG. This new configuration is to offset the capital investment. Time to haul 150 traps using singles versus 15 ten-pot trawls is changing the way snow crab harvesters will potentially fish if the fishery goes to an on-demand-only fishery. This change to trawls from singles would also introduce a small risk of groundline entanglement. It is also important to consider the potential for acoustic disturbance of marine mammals and other key biota, as ODG acoustic signaling should not be another source of anthropogenic stress. The intermittent, low-energy nature of this technology would suggest that this should not be a major concern. But it is important for there to be compliance with acoustic thresholds such as those defined by the US Endangered Species Act 1973 (NOAA 2024c). There is an ongoing study that will provide critical information in this regard (NOAA 2024b). There is also the concern that allowing harvesters into areas closed to VBL fishing would increase fishing vessel noise around the whales.

Gear marking

Progress in the development, testing, use, and enforcement of ODG in areas where multiple fisheries operate, such as the areas where persistent VBLs are now prohibited in the USA under the Atlantic Large Whale Take Reduction Plan, requires a robust gear location marking solution to avoid gear conflict. Such conflict is a concern where fishing and scallop trawlers currently can usually avoid traps using the surface markers attached to VBLs. Promising virtual gear-marking solutions are being proposed by collaborations between some gear manufacturers where multiple gear types can be viewed on a single platform. However, to be equitable, universal, and encouraging competitive pricing, gear marking and recovery must be interoperable within and between each of the different brands of ODG in use. In addition, the screens that display virtual trap locations should be available to all vessels that need to know where bottom gear is set, such as draggers and scallopers. To coordinate and significantly accelerate the development of this universal solution requires strategic investment that would make large-scale experimental fisheries with ODG a practicality in some areas in as little as 1–2 years. However, harvesters in some fishing communities who purchased ODG can be leery of being the few that go out to fish in closed areas using ODG. Social pressure to provide equal opportunity among all harvesters to fish ODG would likely lead to a greater amount of time to equip them with the gear.

At least one proposed solution includes a gear-marking system, whereby information about the gear location at the bottom is collected and transmitted from fishing vessels at sea to a cloud database in near real time Baumgartner 2023 and Fig. 5. For acoustic positioning, a communication standard that allows different manufacturers’ gear on different fishing vessels to collect gear location information and share it with the cloud is required. The standard proposed (Baumgartner et al. ) is currently under development by several manufacturers. Gear location information from this cloud database can then be automatically requested by, and transmitted to, vessels at sea in real time and displayed on commercial chart plotters, thereby seamlessly providing gear location information to harvesters on equipment that they already own. This will enable other fixed bottom gear harvesters and mobile draggers and scallopers to virtually “see” and avoid bottom gear with no surface marker. For this, internet connectivity or a reliable cell connection will be essential for fixed and mobile gear vessels in areas where ODG is in use and the possibility of gear conflict or lost gear is high.

Other proposals for avoiding gear conflict have considered less expensive alternatives for areas where gear density and the risk of gear loss are low (i.e. harvesters do not fish very close to one another). For example, it may be possible to either manually or in an automated fashion mark the deployment of the gear’s surface position as it is deployed with a global positioning system (GPS) receiver, equivalent to dropping a pin on a smartphone.

Acoustic and GPS position data could be uploaded to a cloud-based storage system and is being considered as an option for ease of access for harvesters, regulators, and enforcement agencies. Initial work has been done by several organizations to demonstrate components of various gear marking systems, and studies are underway as to how best to integrate, coordinate, and quickly advance these efforts to fully realize this vision.

Regardless of how virtual gear location is ultimately executed, interoperability between manufacturers’ equipment is essential. Currently, many individuals in the on-demand fishing gear community, including manufacturers and engineers, support the development of open standards for gear location. In addition to improving location accuracy and significantly reducing the chances of permanently losing gear, interoperability standards will likely lead manufacturers to innovate around these standards by offering additional features to compete with other systems. The result of competition is lower costs to the consumer or a product with benefits beyond those of the minimum standards, which may appeal to the consumer. Affordability of ODG will have a large impact on its adoption, and anything that can be done in these relatively early stages of development to control costs will be enormously beneficial in the long run.

The harvesters who tested ODG were generally aware that the Gear Team had access to the virtual gear locations. Anecdotally, none of them have ever expressed concern about this. Aside from the project itself, members of the Gear Team have discussed with harvesters the possibility of this gear being used in a regulated program where the gear locations would be visible to regulators and other mariners within future specified viewing radii. These conversations were generally positive, as the fixed gear users saw the benefit of finally having a way for bottom-tending mobile gear vessels to see the orientation of trawls on a screen in all weather conditions. This ability to visualize gear gave the impression that more accountability would be put on the mobile gear fleet when it comes to gear conflict. This is the view of many of our collaborators, but the idea of sharing gear locations via the cloud is still novel in the USA and will be worked out through the Fisheries Council and public comment processes. Some harvesters have suggested that dockside viewing of gear locations, providing individual identification of gear ownership is protected, could be advantageous in reducing gear conflict and for enforcement. Others have argued that gear location should be kept proprietary and only visible within a specific distance of the gear location (e.g. within 5 miles) to avoid gear conflict. Gear manufacturers are seeking guidance from managers as to what data should be available to further advance software and gear marking development. Currently harvesters from surface gear marking requirements for this limited purpose.

Barriers

Barriers to the implementation of on-demand fishing in the NE USA are technical, economical, regulatory, and cultural in nature. While the gear may be commercially available for purchase, it is expensive and not ready from a permitting perspective. The National Marine Fisheries Service (NMFS), the Atlantic States Marine Fisheries Commission, and multiple state agencies manage commercial fisheries and issue implementing regulations that require surface buoys to mark the location of bottom-stowed gear. Currently, anyone fishing with ODG must do so under an Exempted Fishing Permit (EFP) as part of a broader gear trial that exempts fishers from surface gear marking requirements for this limited purpose. Lobster fishing without surface gear markings increases the likelihood of gear conflicts between lobster harvesters and other fixed gear types, as well as mobile gear fisheries that contact the bottom operating in the same areas. In the future, both the mobile and fixed gear fleets will need to “see” data in real time. Once that emerging technology is fully developed, new regulations allowing on-demand fishing without an EFP can be issued. In the near term, most of the on-demand fishing under the EFP is occurring within the Atlantic Large Whale Take Reduction Plan restricted areas to allow fishing opportunities during a time when the use of static VBLs is otherwise prohibited. A parallel process for rulemaking by the Fisheries Management Councils under the Magnuson Stevenson Act is underway to allow commercial fishing without static VBLs. However, as the Fishery Management Councils are responsible for managing both static and mobile gear fisheries, demonstrating the ability to avoid gear conflicts without surface marking buoys was prioritized prior to further rulemaking. In addition, cultural concerns regarding where and when permitting commercial fishing with ODG without an EFP have been a barrier. Despite no management proposals to require the use of ODG outside of restricted areas, some harvesters have raised concerns that allowing its use more broadly will lead to more widespread requirements in the future. These concerns are underscored by the primary incentives to trial gear being driven almost exclusively by harvesters who have been impacted by seasonal restricted areas, which prevent the use of static vertical lines.

Residual entanglement risk

The transition from the vernacular of “ropeless” to “on-demand” or “pop-up” gear was largely incentivized by the fishing community to clarify that line use in the fishery would not be prohibited. Lines, including the groundlines used to connect traps to a trawl and gangions that connect the traps to the groundlines, remain an essential mechanism for commercial trap-pot fishing. In addition, at least some versions of ODG include stowed VBLs. Broadscale regulatory efforts to reduce entanglement risk from groundlines went into effect in 2009, requiring the use of sinking groundlines throughout most fixed gear fisheries along the US east coast. Data on the effectiveness of this groundline rule are limited and did not show a significant correlation to entanglement risk for humpback whales (Robbins and Pace 2018). However, the researchers found a correlation between a reduction in vertical lines and survivorship of humpback whales. Concerns regarding the potential entanglement of gear that deployed prior to a harvester coming on site were discussed, and lines used by the gear trials were uniquely marked as a result. No gear removed from whales has been identified to ODG from US trials to date. The temporary deployment of vertical lines or introduction of groundlines in the water column when ODG is being retrieved is not fully risk averse, but we believe that the risk is insignificant as compared to traditional fishing methods.

Next steps

At present, US regulators seasonally restrict the use of VBLs in over 63 000 square miles of fishing areas along the US east coast to reduce entanglement risk. In Canada, acoustic detections of whales by hydrophones (underwater microphones), and visual sightings of right whales from vessels and aircraft, will trigger temporary and season-long fishing closures (DFO 2024). ODG trials should continue and expand to further develop these systems and increase first-hand knowledge of the gear to provide fishing communities with viable solutions to access fishing areas closed to VBLs. The spatial extent of trials and of the gear types and fisheries involved should all increase. The number of different on-demand systems being trialed should be as large as practical, with international collaborations where feasible. Improvements in both gear design and in the availability and implementation of through-hull transducers will improve performance and retrieval times. Efforts should be made to streamline and accelerate permit processing to fish without VBLs until fishing without a surface buoy is commercially viable and regulated.

General lessons

We learned through this project that while external factors may drive the need to modify long-standing industry practices, the ability to effect change is dependent on identification of key industry stakeholders, quick mobilization of resources, immediate response to industry needs, and effective communication skills.

Acknowledgments

Three anonymous reviewers and the editor contributed extensive and valuable comments and suggestions, for which we are very grateful. We sincerely thank participating harvesters for their investment of time and resources, and critical thinking in this project. Our collaborators were hugely helpful: Heidi Henninger, Christin Khan, Zack Klyver, Robert Martin, and Marc Palombo. We thank Sean Brillant, Nicholas Hopkins, Kim Sawicki, Geoff Shester, Edward Tripple, Elizabeth Vézina, and Gregory Wells for valuable discussions about how to categorize on-demand fishing data. Trials were undertaken under annual Exempted Fishing Permits # 20019, 21008, 22002, and 23008.

Author contributions

E.M. and H.M.: project management, conceptualization, methodology, investigation, writing—review & editing, visualization. R.A.-S., E.F., and B.S.: conceptualization, methodology, investigation, writing—review & editing, visualization, funding. M.A., M.B., and B.G.: methodology, investigation, writing—review & editing, visualization. M.M.: conceptualization, initial draft writing—review & editing, visualization, funding.

Conflict of interest

The results and conclusions, as well as any views or opinions expressed herein, are those of the authors and do not necessarily reflect the views of NMFS, NOAA, or the Department of Commerce.

Funding

This work was supported by the Annenberg Foundation, Arthur L. and Elaine V. Johnson Foundation, Binnacle Fund at the Tides Foundation, Conservation Law Foundation, Donna & Ron Chadderton, International Fund for Animal Welfare, New England Biolabs, NOAA, NOAA Bycatch Reduction Engineering Program NA23NMF4720409, Paul M. Angell Family Foundation, SeaWorld Conservation Fund, Sheehan Family Companies, Whale and Dolphin Conservation, and Woods Hole Oceanographic Institution.

Data availability

Per vessel data are not available to protect the privacy, and intellectual property, of the individual harvesters.