Bycatch In Commercial Fisheries Research Articles

A probabilistic time geographic approach to quantifying seabird‐vessel interactions

AbstractAccounting for uncertainty is essential for precautionary approaches to managing seabird bycatch in commercial fisheries. However, there is no existing mechanism to explicitly quantify the uncertainty of seabird‐vessel interactions (i.e. co‐occurrence in space and time). Here we develop a time geographic method to measure the probability of individual birds encountering (co‐occurring within 30 km) and attending (within 5 km) individual fishing vessels. The approach involves creating voxel‐based probabilistic space–time prisms (PSTPs) to model the movements of individual birds and vessels, with trajectory data from bird‐borne GPS devices and vessel Automatic Identification Systems (AIS). We intersected these PSTPs to quantify the probability of interaction between bird‐vessel pairs over time and space. We demonstrate the approach with a case study of interactions of Endangered Toroa (Antipodean Albatross; Diomedea antipodensis antipodensis) with pelagic longline vessels in part of the South Pacific high seas. We found 15 vessels within 150 km and 3 h of two birds, yet interaction occurred with only two of those vessels. We visualised the probability of encounter and attendance over time and space and determined that interactions lasted several hours each (up to 6.2–14.1 h attendance, 20.8–26.1 h encounter for one bird‐vessel pair). Our time geographic approach adds to existing tools to quantify seabird bycatch risk by providing an explicit measure of uncertainty of seabird‐vessel interactions. We provide a flexible methodological pathway and R scripts, the application of which would allow managers to estimate interaction probability for multiple marine species and fisheries, including those with lower‐resolution positional datasets.

Fishery-independent and -dependent movement data aid in defining the stock structure of a data-deficient billfish

The shortbill spearfish (Tetrapturus angustirostris) is a data-deficient billfish frequently encountered near the Main Hawaiian Islands where it is taken as non-target bycatch in commercial fisheries. The lack of information on the species’ movement and stock structure is a primary management concern given uncertainty in its population dynamics and the lack of a formal stock assessment. Here, we combine fishery-independent satellite telemetry with fishery-dependent conventional tagging to describe the movement ecology of shortbill spearfish in the central North Pacific and contextualize it with respect to stock structure and the management considerations implicit with that structure. We show that shortbill spearfish are highly migratory like other billfishes and large pelagics, exhibiting multiple scales of movement with general fidelity to the region of the Hawaiian Islands and surrounding high seas but no discernible seasonality to their movements. The species’ displacements from the island group into areas beyond national jurisdiction result in exposure to multiple distinct commercial fishing fleets, suggesting the need for multi-national cooperation in quantifying harvest. By comparing the limited sources of information on shortbill spearfish with the far more expansive knowledge base of other highly migratory fishes, we suggest a first-order division of stocks between the North and South Pacific. Continued interdisciplinary efforts are needed to confirm and further understand the proposed stock structure.

The implementation of ACAP Best Practice Advice to mitigate seabird bycatch in fisheries: Issues and options

The Agreement on the Conservation of Albatrosses and Petrels (ACAP) is a multilateral agreement which strives to conserve albatrosses and petrels by coordinating international activities to mitigate threats to their populations. One of the major threats that seabirds face is fisheries-induced mortality, or bycatch. In recognition of the serious nature of this problem, ACAP established a Seabird Bycatch Working Group (SBWG) to advise on actions that will assist in the mitigation and reduction of seabird interactions with fisheries. The SBWG regularly examines the range of measures available that can minimise bycatch and has developed “best practice advice” (BPA), a suite of tools and methods for trawl and longline fisheries. This BPA has been widely promoted by ACAP Parties and others within jurisdictions and at Regional Fisheries Management Organisations (RFMOs) and CCAMLR other over the last 10 years. To assess the levels of implementation of ACAP’s BPA for industrial fisheries we employed both a qualitative and semi-quantitative multiple method research design that comprised content analysis of documents and meeting reports from ACAP meetings, a review of current seabird conservation measures of all tRFMOs that had members which were also ACAP parties, and by conducting a survey that asked 13 questions in relation to the uptake and adoption of ACAP BPA. We confined our analysis to pelagic longline and trawl fisheries within the jurisdictions of both ACAP parties and non-parties. Our research identified a number of key gaps in the uptake of the BPA guidelines in these fisheries. Complete uptake of BPA was poor by ACAP Parties both within their jurisdictions, and in high seas fisheries managed through RFMOs. For Parties, the level of uptake was difficult to assess accurately because reporting to the Agreement has thus far been inadequate for this purpose. Uptake of BPA in high seas fisheries by non-parties and RFMos was also poor and unlikely to improve while ACAP Parties are unable to demonstrate commitment to their use in all national fisheries. The study findings provided advice and recommendations on addressing impediments to uptake that could lead to improved management of seabird bycatch in commercial fisheries.

Variability in billfish vertical distribution and fishing interactions driven by environmental conditions in the Eastern Tropical Pacific Ocean

Abstract Blue marlin (Makaira nigricans) and sailfish (Istiophorus platypterus) are ecologically important predators and valuable species throughout the world’s recreational, commercial, and subsistence fisheries. Comparing multi-species vertical habitat use can inform ecological uncertainties such as inter-species competition, as well as relative vulnerabilities to fishing activities. In this study, we identified key differences in both depth use and which environmental variables drive these selections, which highlights the variability in the catchability both as target species in recreational fisheries and bycatch in commercial fisheries. To understand these two species’ vertical habitat use, we examined depth profiles from 26 sailfish and 48 blue marlin tagged with pop-up satellite archival tags deployed in the Eastern Tropical Pacific Ocean. While both species are surface-oriented, we found evidence of vertical niche partitioning where sailfish spend more time at deeper depths than blue marlin. Blue marlin recorded an average mean depth of 18.5 m (±10.8 m) during daytime and 5.2 m (±5.5 m) at nighttime (Figure 31a), while sailfish recorded an average mean depth of 23.6 m (±11.1 m) during daytime and 6.45 m (±4.64 m) at nighttime. Generalized additive mixed models fitted to predict mean and max depth revealed sea level anomaly (SLA), oxygen, sea surface temperature, and mixed layer depth as significant predictors of vertical habitat use for both species. We also examined catch logs from three recreational fishing lodges in Central America to understand the influence of environmental conditions on billfish sightings per unit effort. For blue marlin and sailfish, SLA was a significant predictor in each of the four depth models (mean day, mean night, max day, max night). SLA was the variable with highest percent deviance explained for all four sailfish depth models and three of the four blue marlin depth models and had a positive relationship with all response variables for all four blue marlin depth models and three sailfish depth models (mean daytime, max daytime, max nighttime), where higher positive SLA values were associated with deeper depth responses.

Spatial and temporal genetic stock composition of river herring bycatch in southern New England Atlantic herring and mackerel fisheries

Anadromous river herring (alewife and blueback herring) persist at historically low abundances and are caught as bycatch in commercial fisheries, potentially preventing recovery despite conservation efforts. We used newly established single-nucleotide polymorphism genetic baselines for alewife and blueback herring to define fine-scale reporting groups for each species. We then determined the occurrence of fish from these reporting groups in bycatch samples from a Northwest Atlantic fishery over four years. Within sampled bycatch events, the highest proportions of alewife were from the Block Island (34%) and Long Island Sound (22%) reporting groups, while for blueback herring the highest proportions were from the Mid-Atlantic (47%) and Northern New England (24%) reporting groups. We then quantified stock-specific mortality in a focal geographic area (∼3500 km2, including Block Island Sound) of high bycatch incidence and sampling effort, where the most accurate estimates of mortality could be made. During this period, we estimate that bycatch took about 4.6 million alewife and 1.2 million blueback herring, highlighting the need to reduce bycatch mortality for the most depleted river herring stocks.

Uncertainty, anxiety, and optimism: Diverse perspectives of rainbow and steelhead trout fisheries governance in British Columbia

Inland fisheries are complex social-ecological systems that can generate important nutritional, economic, cultural, and recreational benefits. Effective management of these systems for multiple user-groups requires an understanding of the complex natural and human dimensions interactions within them. We examine the perceptions of stakeholders, Indigenous rightsholders, and regulatory/governance groups on the current and future status of Oncorhynchus mykiss (including their resident form – rainbow trout – and their anadromous form – steelhead) populations and fisheries in British Columbia (BC), Canada from 65 qualitative interviews and 1029 quantitative survey responses. Participants generally did not believe resident rainbow trout were threatened at the provincial level but were definitive in assessing anadromous steelhead trout as threatened. Habitat alterations, water temperature extremes, and climate change, were key threats identified for all forms of O. mykiss while bycatch in commercial fisheries and predation pressure from pinnipeds were specifically identified threats for steelhead trout. Anglers did not perceive recreational fishing pressure as a key threat in contrast to regulatory and governance groups. Fisheries managers were praised for stocking programs and managing small lakes fisheries but criticized for not doing enough to protect fish populations, for an unwillingness to challenge or confront commercial and Indigenous interests which infringe on conservation, and for a lack of aquatic monitoring. Three factors identified by participants contribute to fishery mismanagement, inaction, and decision paralysis: (1) insufficient resources (funding, staff, time), (2) confusion in jurisdictional authority between provincial and federal governments, and (3) organizational structure of natural resource management agencies which are not autonomous from competing commercial and industrial objectives and directions. Despite conservation being purported as the highest priority of fisheries managers, economic, social, and political drivers are perceived as increasingly influencing conservation decisions and actions. These findings can inform fisheries management and conservation decisions, policies and practices to ensure that they are more salient, robust, legitimate, and effective.

Commercial fishery bycatch risk for large juvenile and adult smalltooth sawfish (Pristis pectinata) in Florida waters

Abstract Incidental catch of marine species can create ecological and economic issues, particularly for endangered species. The smalltooth sawfish (Pristis pectinata) is endemic to the Atlantic Ocean and listed as Endangered in the US Endangered Species Act. One of its major threats is bycatch mortality in commercial fisheries. Despite the protection afforded by the US Endangered Species Act, smalltooth sawfish are still captured as bycatch in commercial fisheries. Acoustic and satellite tag data collected on 59 sawfish between 2011 and 2019 were analysed to assess commercial fishery bycatch risk for large juveniles and adults off Florida. This study focused on shrimp trawl, south‐east coastal gillnet, and shark bottom longline fisheries, as these were identified in the recovery plan as having the greatest potential threats to recovery. Bycatch risk associated with the shrimp trawl fishery was significantly higher than the other fisheries, indicating that this fishery currently poses the greatest threat to recovery. Bycatch risk was concentrated in all seasons in the Gulf of Mexico adjacent to the lower Florida Keys for the shrimp trawl fishery, off Cape Canaveral in the south‐east coastal gillnet fishery, and in the Atlantic Ocean adjacent to the Florida Keys in the shark bottom longline fishery. Tagging location and sex were predictors of bycatch risk. Individuals tagged in Charlotte Harbor had the highest shrimp trawl bycatch risk. Females tagged in south Florida tended to reside in the deepest water, which is where shrimp trawl effort is highest. Therefore, females may be at more risk in these deeper waters. Results from this study indicate a year‐round closure of waters off south‐west Florida to the shrimp trawl fishery between Charlotte Harbor and the western Florida Keys would reduce sawfish bycatch, and thus mortality, which is in line with recovery plan goals.

Contrasting patterns of population structure in commercially fished sawsharks from southern Australian waters

In the waters of southeast Australia, two species of sawshark—the common (Pristiophorus cirratus) and southern (Pristiophorus nudipinnis) sawshark—are frequent by-catch in commercial fisheries. While harvesting of both species is currently considered sustainable, there has been no investigation of whether P. cirratus and P. nudipinnis display genetically distinct populations throughout their ranges. Such information is necessary for effective management of these species in commercial fisheries. This study examined population structure in both sawshark species through analysis of two mitochondrial genes: cytochrome b (Cyt-b) and NADH dehydrogenase subunit 5 (ND5). Results indicated contrasting levels of population structure, with P. cirratus consisting of two, possibly three, genetically distinct populations with two mitochondrial lineages and P. nudipinnis consisting of a single population. Tests for population expansion also highlighted differences between the two species. Population expansion was detected for the entire P. nudipinnis population, whereas this was only the case for one mitochondrial lineage in P. cirratus. The entire P. cirratus population displayed signals of demographic stability. It is hypothesised that the opening and closing of Bass Strait during glacial-interglacial cycles played a major role in shaping the population structure and expansion signatures observed in this study. Mitochondrial data also suggest that patterned and uniform brown P. cirratus are the same species. Fisheries managers should consider adopting two management units in southern Australia—one along the east coast (for the eastern P. cirratus population) and one along the south coast (for the southern P. cirratus population and the single P. nudipinnis population).

Distributions of threatened skates and commercial fisheries inform conservation hotspots

Bycatch in commercial fisheries is a pressing conservation concern and has spurred global interest in adopting ecosystem-based management practices. To address such concerns, a thorough understanding of spatiotemporal relationships among bycatch species, their environment and fisheries is required. Here we used a generalized linear mixed model framework incorporating spatiotemporal random effects to model abundance patterns for 3 skate species caught as bycatch in commercial fisheries (thorny skate Amblyraja radiata, winter skate Leucoraja ocellata and smooth skate Malacoraja senta), as well as 10 target species on the Scotian Shelf, NW Atlantic. Spatiotemporal estimates of relative abundance for at-risk skates within the years 2005-2015 were modelled from research trawl survey data and overlaid with those for target species to identify hotspots of bycatch risk. In addition, abundance estimates for at-risk skates within the years 1975-1985, a period of higher stock abundance, were used to identify areas of previously important habitat. Historically, skate species densely occupied areas near Sable Island and Banquereau Banks, Georges Bank and the Bay of Fundy. Bycatch hotspots between at-risk skates and commercial targets were identified in regions across the Scotian Shelf. These hotspots were independently validated by predicting species presence from at-sea observer data that monitor skate bycatch directly. We discuss spatial relationships between target and bycatch species, highlighting limitations of at-sea observer programmes that this method helps to address. This framework can be applied more broadly to inform ecosystem management and priority areas for conservation or fisheries regulation.

Incorporating depth into habitat use descriptions for sailfish Istiophorus platypterus and habitat overlap with other billfishes in the western North Atlantic

The sailfish Istiophorus platypterus is a circumglobal billfish species. It is commonly targeted in recreational fisheries and caught as by-catch in commercial fisheries, and therefore fisheries management would benefit from an enhanced understanding of basic patterns of the species’ daily and seasonal movements. Between 2002 and 2007, 87 billfish were tagged with pop-off satellite archival tags in the Atlantic waters off the coast of South Carolina, USA, including sailfish (n = 54), blue marlin Makaira nigricans (n = 15), and white marlin Kajikia albida (n = 18). Only fish meeting specific tag program criteria and length of tag attachment were selected for further analysis (sailfish, n = 19; blue marlin, n = 4; white marlin, n = 3). Differential horizontal and vertical movement patterns were observed within sailfish by season. Two- and three-dimensional (3D) analyses showed differential spatial niche use by sailfish. Among the istiophorid species, 3D analysis showed less overlap when occupying similar horizontal areas. The results from this study, in conjunction with similar studies from other areas, provide a better understanding of habitat usage that can be applied to address uncertainties in ecology or management, such as characterization of stock structure, identifying potential spawning habitat or intra-specific competition, providing correction factors for indices of abundance, and characterizing vulnerability to fishing gear.

Compliance with marine mammal protection: Focus groups reveal factors in commercial fishermen's decisions

In researching non-compliance with use of an acoustical device (a pinger), required under the Marine Mammal Protection Act (MMPA) to protect harbor porpoise (Phocoena phocoena) in the Northeast U.S., focus group research provided insight on facets of non-compliance not previously considered. This method of group interview can reveal individuals' knowledge and perceptions of the legitimacy of a problem, process and solution along with social (including legitimacy) and economic factors, and cultural norms that can influence compliance or other decisions. In addition, each participant filled out a short survey on topics we already expected to be of interest. We investigate how these factors from the focus group discussion and the survey influence a fisherman's decision to comply with marine mammal regulations. Prior to the focus groups we expected participants to either fully comply or not comply at all with pinger requirements. By using multi-method research, we found that there was a third group that included fishermen that mostly complied but eliminated one mandatory pinger for safety reasons. Using harbor porpoise as a case study, we provide insight on approaches to improve compliance, a key component of a successful management plan designed to reduce marine mammal bycatch in commercial fisheries.

At-sea spatial usage of recently weaned grey seal pups in Iceland

Although grey seals (Halichoerus grypus) are the focus of considerable research effort throughout much of their North Atlantic breeding range, little is known about grey seal movement ecology in Iceland. This is surprising given the long history of grey seal exploitation in Iceland and because grey seals are common bycatch in commercial fisheries. Here, for the first time, we deployed satellite tags on five grey seals in Iceland to quantify the at-sea spatial usage of recently weaned pups during their first year of life. Maximum foraging trip distance ranged from 20 to 160 km for individual pups, while maximum duration ranged from 4.3 to 20.8 days. Individual differences in foraging trip metrics indicated two broad strategies. Specifically, pups either remained near the deployment location or dispersed to the east of Iceland, reaching a total distance of > 300 km from the deployment location. Foraging trips were, however, typically restricted to the continental shelf, which presumably reflects a preference for benthic foraging, as is reported for grey seals at other breeding locations. Our preliminary findings highlight the importance of near-shore waters to recently weaned grey seal pups in Iceland and suggests that coastal fisheries are a prevalent threat. However, additional research is required to quantify interactions between grey seals and commercial fisheries, which in turn, would improve the efficacy of conservation and management efforts.

The Importance of Education and Community Engagement Towards Sea Turtle Conservation

In order to cope with the historic unsustainable use of resources and lack of concern that humans have for the environment, scientists and educators have “elected” species they believe can help to conserve natural resources. As a beloved and charismatic species, sea turtles are often chosen as ambassadors to encourage a change in public perception of the importance of healthy ecosystems. Sea turtles are some of the most vulnerable species in marine ecosystems, yet the roles they play as habitat engineers, predators, prey, and facilitators of nutrient cycling are becoming more apparent as human activities have reduced their numbers worldwide. Poaching of their nests, bycatch in commercial fisheries, and capture for meat and carapaces are drastically affecting critical turtle populations and placing them closer to extinction. However, by playing vital roles in the delicate balance of marine ecosystems, they help educators encourage changes in behavior that help protect sea turtles and the marine ecosystems that rely on them. This paper highlights the importance of education in conservation and demonstrates the use of charismatic megafauna, like the sea turtle, in the fight to save the environment by showcasing the role that sea turtles play in marine ecosystems as well as the success of Equipo Tora Carey<em>. </em>

The Northern Extent of Pacific White-Sided Dolphin (Lagenorhynchus obliquidens) Distribution in the Eastern North Pacific

We present updated distribution information for the Pacific White-sided Dolphin (Lagenorhynchus obliquidens, PWSD) in the southeastern Bering Sea, including Bristol Bay. The northern extent of this dolphin's range currently includes Bristol Bay and a 150-km swath north of the Aleutian Island chain, and presence in the Bering Sea has been described as rare. Our review of National Marine Fisheries Service marine mammal survey data (1991 to 2010) and sighting reports from sources such as the Platforms of Opportunity Program, whaling and fisheries catch records, and naturalist reports (1975 to 2016) found numerous sightings (n = 191) and year-round presence within the current range. We also found 18 sightings, 2 of which were bycatch in commercial fisheries, that occurred north of the existing range and in all seasons. Based on these results, we suggest PWSD presence in the Bering Sea is not rare, occurs year-round, extends farther north than shown on current range maps, and that site-fidelity may occur in areas near and within Bristol Bay.

Latent Gaussian models to predict historical bycatch in commercial fishery

Knowledge about how many fish that have been killed due to bycatch is an important aspect of ensuring a sustainable ecosystem and fishery. We introduce a Bayesian spatio-temporal prediction method for historical bycatch that incorporates two sources of available data sets, fishery data and survey data. The model used assumes that occurrence of bycatch can be described as a log-linear combination of covariates and random effects modeled as Gaussian fields. Integrated Nested Laplace Approximations (INLA) is used for fast calculations. The method introduced is general, and is applied on bycatch of juvenile cod (Gadus morhua) in the Barents Sea shrimp (Pandalus borealis) fishery. In this fishery we compare our prediction method with the well known ratio and effort methods, and make a strong case that the Bayesian spatio-temporal method produces more reliable historical bycatch predictions compared to existing methods.

Human-mediated extirpation of the unique Chatham Islands sea lion and implications for the conservation management of remaining New Zealand sea lion populations.

While terrestrial megafaunal extinctions have been well characterized worldwide, our understanding of declines in marine megafauna remains limited. Here, we use ancient DNA analyses of prehistoric (<1450-1650 AD) sea lion specimens from New Zealand's isolated Chatham Islands to assess the demographic impacts of human settlement. These data suggest there was a large population of sea lions, unique to the Chatham Islands, at the time of Polynesian settlement. This distinct mitochondrial lineage became rapidly extinct within 200years due to overhunting, paralleling the extirpation of a similarly large endemic mainland population. Whole mitogenomic analyses confirm substantial intraspecific diversity among prehistoric lineages. Demographic models suggest that even low harvest rates would likely have driven rapid extinction of these lineages. This study indicates that surviving Phocarctos populations are remnants of a once diverse and widespread sea lion assemblage, highlighting dramatic human impacts on endemic marine biodiversity. Our findings also suggest that Phocarctos bycatch in commercial fisheries may contribute to the ongoing population decline.

Seasonal and Diel Bathythermal Distributions of Lake Whitefish in Lake Huron: Potential Implications for Lake Trout Bycatch in Commercial Fisheries

AbstractDepths and temperatures recorded during 2003–2005 by archival tags implanted in Lake Whitefish Coregonus clupeaformis and in Great Lakes origin (GLO) and New York Finger Lakes origin (FLO) strains of Lake Trout Salvelinus namaycush were used to compare seasonal diel depth and temperature distributions in Lake Huron. Seasonal depth distributions were examined to determine if species differences could be exploited to reduce bycatch of Lake Trout in commercial Lake Whitefish gill‐net fisheries. Both GLO and FLO Lake Trout used deeper and colder waters than Lake Whitefish during daylight and dark. Temperature differences between species were greatest during periods of stratification when behavioral thermoregulation was possible. Other than during spawning periods, the greatest depth and temperature separation occurred in late July between FLO Lake Trout (37.0 m; 6.5 ºC) and Lake Whitefish (25.1 m; 10.2 ºC). If maximum depths of gill nets were regulated seasonally to between 25 and 35 m, ≥ 50% of the Lake Whitefish population would be vulnerable while avoiding 89% or more of Lake Trout. Lake Trout percentages targeted under such regulations would be lowest in late July (GLO = 8% and FLO = 11%) and early August (GLO = 4% and FLO = 7%). However, archival tags measure fish depth and not location or bottom depth, and modal depths of gill‐net effort for Lake Whitefish (38 to 57 m) exceeded those from the Lake Whitefish archival tag data. This discrepancy suggests that many Lake Whitefish might be pelagic above the reach of bottom‐set gill nets, so depth restrictions could be less effective in reducing Lake Trout bycatch than suggested by our data. A further implication is that use of gill nets suspended above the bottom to target pelagic Lake Whitefish could also reduce bycatch while potentially increasing Lake Whitefish harvest.Received August 19, 2015; accepted February 21, 2016 Published online June 28, 2016

Fisheries conservation on the high seas: linking conservation physiology and fisheries ecology for the management of large pelagic fishes.

Populations of tunas, billfishes and pelagic sharks are fished at or over capacity in many regions of the world. They are captured by directed commercial and recreational fisheries (the latter of which often promote catch and release) or as incidental catch or bycatch in commercial fisheries. Population assessments of pelagic fishes typically incorporate catch-per-unit-effort time-series data from commercial and recreational fisheries; however, there have been notable changes in target species, areas fished and depth-specific gear deployments over the years that may have affected catchability. Some regional fisheries management organizations take into account the effects of time- and area-specific changes in the behaviours of fish and fishers, as well as fishing gear, to standardize catch-per-unit-effort indices and refine population estimates. However, estimates of changes in stock size over time may be very sensitive to underlying assumptions of the effects of oceanographic conditions and prey distribution on the horizontal and vertical movement patterns and distribution of pelagic fishes. Effective management and successful conservation of pelagic fishes requires a mechanistic understanding of their physiological and behavioural responses to environmental variability, potential for interaction with commercial and recreational fishing gear, and the capture process. The interdisciplinary field of conservation physiology can provide insights into pelagic fish demography and ecology (including environmental relationships and interspecific interactions) by uniting the complementary expertise and skills of fish physiologists and fisheries scientists. The iterative testing by one discipline of hypotheses generated by the other can span the fundamental-applied science continuum, leading to the development of robust insights supporting informed management. The resulting species-specific understanding of physiological abilities and tolerances can help to improve stock assessments, develop effective bycatch-reduction strategies, predict rates of post-release mortality, and forecast the population effects of environmental change. In this synthesis, we review several examples of these interdisciplinary collaborations that currently benefit pelagic fisheries management.

Characterization of seabird bycatch in eastern Canadian waters, 1998–2011, assessed from onboard fisheries observer data

Abstract Seabird bycatch in commercial fisheries has been a growing conservation concern over the past 25 years. Large‐scale fisheries employing gears known to incidentally catch seabirds operate off eastern Canada, however, regional bycatch information is limited. Using data collected from 1998–2011 by observers onboard Canadian domestic and foreign vessels, fishery sectors and target fisheries taking seabirds were identified, as were the seabirds most frequently taken. In addition, maps of seabird bycatch rates were used to identify localized areas where catch rates were high. Seabird bycatch was widespread. Despite generally low observer coverage, &gt; 5000 bird deaths were recorded; most observed mortalities occurred in gillnet and longline sectors during summer and autumn. While the overall magnitude of seabird bycatch has likely decreased substantially since closure of the Atlantic cod Gadus morhua and Atlantic salmon Salmo salar gillnet fisheries in 1992, localized areas with high bycatch rates persist. For example, in Baffin Bay and Davis Strait, bycatch rates of northern fulmars Fulmarus glacialis were high in gillnet and longline fisheries targeting Greenland halibut Reinhardtius hippoglossoides near breeding colonies. In offshore areas of the Grand Bank, catch rates of migrant shearwaters (Puffinus and Calonectris spp.) were high in deep‐set gillnet fisheries for Greenland halibut and monkfish Lophius americanus during summer. In inshore regions of eastern Newfoundland, gillnets set for Atlantic cod near breeding colonies resulted in high bycatch rates of murres Uria spp. and shearwaters during summer. High bycatch rates were also observed in pelagic longline fisheries along the Scotian Shelf. While the observer data have highlighted several localized areas with high bycatch rates, information for inshore gillnet fisheries, which take seabirds but are poorly covered by the observer programme, and regional information on fishing effort must both be considered for comprehensive assessment of seabird risk areas and consequent management needs in eastern Canada. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Influence of fishing practices on lake trout bycatch in the Canadian lake-whitefish commercial fishery in Lake Huron

Rehabilitation of lake trout (Salvelinus namaycush) populations is a priority for fisheries management in the upper Laurentian Great Lakes. In Lake Huron, lake trout are frequently caught as bycatch in the commercial fishery for lake whitefish (Coregonus clupeaformis). Given the frequency of lake trout capture and the importance of limiting mortality for achieving rehabilitation goals, understanding factors that affect lake trout bycatch is valuable. We used catch and effort data from commercial logbooks and onboard observer reports to assess potential effects of factors in the operation of the lake whitefish fishery on lake trout bycatch and to develop standardized indices of lake trout abundance. Factors considered in our analysis were season, mesh size, region, and license holder, which were recorded in both datasets, and set type and depth, which were only recorded in the observer dataset. In general, we found that environmental factors affected whether lake trout bycatch occurred, but that if bycatch occurred, factors related to the fishing gear affected its magnitude. Although we observed seasonal interactions with depth and mesh size, the probability of bycatch was lowest in shallow waters, and the magnitude of bycatch was lowest in shallow waters, alternative set types, and larger mesh sizes. Standardized indices of lake trout abundance from both datasets gave comparable estimates of relative trends; an increase in abundance up to 2004–2005 followed by a decline. Our findings show utility for the use of the observer dataset from the lake whitefish fishery as part of lake trout management in Lake Huron.