Estimating the Discard Mortality of Atlantic Cod in the Southern Gulf of Maine Commercial Lobster Fishery

2020 ◽  
Vol 40 (5) ◽  
pp. 1252-1262
Author(s):  
B. B. Sweezey ◽  
C. W. Capizzano ◽  
J .A. Langan ◽  
H. P. Benoît ◽  
E. W. Hutchins ◽  
...  
Keyword(s):  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Discard Mortality ◽  
Lobster Fishery

scholarly journals Estimating and mitigating the discard mortality of Atlantic cod (Gadus morhua) in the Gulf of Maine recreational rod-and-reel fishery

2016 ◽  
Vol 73 (9) ◽  
pp. 2342-2355 ◽  
Author(s):  
Connor W. Capizzano ◽  
John W. Mandelman ◽  
William S. Hoffman ◽  
Micah J. Dean ◽  
Douglas R. Zemeckis ◽  
...  
Keyword(s):  
Best Practice ◽  
Gadus Morhua ◽  
Fishery Management ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Related Factors ◽  
Discard Mortality ◽  
Recreational Fishery ◽  
Receiver Array ◽  
Management Plans

Abstract In recent years, the recreational contribution to the total catch of Atlantic cod (Gadus morhua) in the Gulf of Maine (GOM) has increased with recreational discards outnumbering recreational landings by 2:1. However, the discard mortality (DM) rate of cod released in the recreational fishery remains poorly understood, thus contributing to the uncertainty in stock assessments and fishery management plans. The current study examined the capture-related factors most detrimental to cod DM in the GOM recreational rod-and-reel fishery. Atlantic cod (n = 640; 26.0–72.0 cm) were angled from June–October 2013 on southern Jeffreys Ledge in the western GOM using fishing gear representative of the local recreational fishery. A subset (n = 136) was also tagged with pressure-sensing acoustic transmitters before being released into an acoustic receiver array (n = 31) deployed to monitor survival up to 94 days. To properly model DM up to the fishery-wide level, all cod were visually assessed for capture-related injuries according to a four-level injury score index. Mean tackle-specific DM rates of 15.4 and 21.2% were estimated for bait- and jig-captured cod, respectively, with an overall 16.5% mean DM rate for the 2013 GOM recreational cod fishery. Twenty-nine cod tagged with acoustic transmitters were identified as dead, where the majority (∼90%) died within 16 h post-capture. Upon evaluation with a specifically adapted parametric survival analysis, greater incidence of mortality was attributed to the capture and handling process (rather than release) for moderately and severely injured cod. Based on the capture-related factors associated with the highest injury rates, we recommend minimizing fight and handling times, avoiding areas with small cod, educating inexperienced anglers, and favouring bait over jigs to mitigate mortality. Results will continue to inform the development of fishery management plans and enhance survival through dissemination of “best practice” techniques to fishery stakeholders.

Oxidative stress, DNA damage and p53 expression in the larvae of atlantic cod (Gadus morhua) exposed to ultraviolet (290–400 nm) radiation

2001 ◽  
Vol 204 (1) ◽  
pp. 157-164 ◽  
Author(s):  
M.P. Lesser ◽  
J.H. Farrell ◽  
C.W. Walker
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Growth Arrest ◽  
Individual Performance ◽  
Cellular Growth ◽  
Pyrimidine Dimer ◽  
Uvb Radiation

Decreases in stratospheric ozone levels from anthropogenic inputs of chlorinated fluorocarbons have resulted in an increased amount of harmful ultraviolet-B (UVB, 290–320 nm) radiation reaching the sea surface in temperate latitudes (30–50 degrees N). In the Gulf of Maine, present-day irradiances of ultraviolet-A (UVA, 320–400 nm) radiation can penetrate to depths of 23 m and UVB radiation can penetrate to depths of 7–12 m, where the rapidly developing embryos and larvae of the Atlantic cod (Gadus morhua) are known to occur. Laboratory exposures of embryos and larvae of Atlantic cod to ultraviolet radiation (UVR) equivalent to a depth of approximately 10 m in the Gulf of Maine resulted in significant mortality of developing embryos and a decrease in standard length at hatching for yolk-sac larvae. Larvae at the end of the experimental period also had lower concentrations of UVR-absorbing compounds and exhibited significantly greater damage to their DNA, measured as cyclobutane pyrimidine dimer formation, after exposure to UVB radiation. Larvae exposed to UVB radiation also exhibited significantly higher activities and protein concentrations of the antioxidant enzyme superoxide dismutase and significantly higher concentrations of the transcriptional activator p53. p53 is expressed in response to DNA damage and can result in cellular growth arrest in the G1- to S-phase of the cell cycle or to programmed cell death (apoptosis). Cellular death caused by apoptosis is the most likely cause of mortality in embryos and larvae in these laboratory experiments, while the smaller size at hatching in those larvae that survived is caused by permanent cellular growth arrest in response to DNA damage. In addition, the sub-lethal energetic costs of repairing DNA damage or responding to oxidative stress may also contribute to poor individual performance in surviving larvae that could also lead to increases in mortality. The irradiances of UVB radiation that elicit these responses in cod larvae can occur in many temperate latitudes, where these ecologically and commercially important fish are known to spawn, and may contribute to the high mortality of cod embryos and larvae in their natural environment.

The influence of spatially variable and connected recruitment on complex stock dynamics and its ecological and management implications

2019 ◽  
Vol 76 (6) ◽  
pp. 937-949 ◽  
Author(s):  
Lisha Guan ◽  
Yong Chen ◽  
James A. Wilson ◽  
Timothy Waring ◽  
Lisa A. Kerr ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Temporal Trends ◽  
Substantial Reduction ◽  
Management Implications ◽  
Agent Based ◽  
Stock Biomass ◽  
Spawning Stock ◽  
The Individual

To evaluate the influence of spatially variable and connected recruitments at spawning component scale on complex stock dynamics, a typical agent-based complex stock was modeled based on the Atlantic cod (Gadus morhua) stock in the Gulf of Maine. We simulated three scenarios with different degrees of connectivity (i.e., individual exchange) between the spatially variable recruitments of 36 spawning components within four subpopulations under the stock. Subsequently, the temporal trends were compared for different scenarios in age-1 recruitment, spawning stock biomass, and local depletion proportion of the overall complex stock and the individual subpopulations. Results show that increased recruitment connectivity from 0.1–0.2 to 0.6–0.8 between various components tends to increase the productivity and stability of a complex stock at local and global scales and reduce the proportion of depleted components due to overfishing. Moreover, depletions of less productive components may occur without a substantial reduction in the overall complex stock biomass and recruitment.

The influence of forage fish abundance on the aggregation of Gulf of Maine Atlantic cod (Gadus morhua) and their catchability in the fishery

2014 ◽  
Vol 71 (9) ◽  
pp. 1349-1362 ◽  
Author(s):  
David E. Richardson ◽  
Michael C. Palmer ◽  
Brian E. Smith
Keyword(s):  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Distribution Patterns ◽  
Fish Populations ◽  
Dependent Data ◽  
Forage Fish ◽  
Catch Per Unit Effort ◽  
Sand Lance ◽  
Unit Effort

Shifts in the distribution and aggregation patterns of exploited fish populations can affect the behavior and success of fishermen and can complicate the interpretation of fisheries-dependent data. Starting in 2006, coinciding with an increase in sand lance (Ammodytes spp.) abundance, Gulf of Maine Atlantic cod (Gadus morhua) concentrated on Stellwagen Bank, a small (405 km2) underwater plateau located in the southwestern portion of the larger (52 461 km2) stock area. The cod fishery in turn concentrated on Stellwagen Bank. Specifically, the proportion of Gulf of Maine cod landings caught in a single 10-minute square area (260 km2) encompassing the tip of Stellwagen Bank increased from 12% in 2005 to 45% in 2010. An increase in landings per unit effort in the fishery coincided with the concentration of the fleet on Stellwagen Bank. Overall, both fisheries-independent and fisheries-dependent data indicate that an increase in sand lance abundance resulted in cod aggregating in a small and predictable area where they were easily caught by the fishery. More broadly, this work illustrates how changes in the distribution patterns of fish and fisherman can decouple trends in abundance and fisheries catch per unit effort.

scholarly journals Modelling the effects of variation in reproductive traits on fish population resilience

2015 ◽  
Vol 72 (9) ◽  
pp. 2590-2599 ◽  
Author(s):  
Arnault Le Bris ◽  
Andrew J. Pershing ◽  
Christina M. Hernandez ◽  
Katherine E. Mills ◽  
Graham D. Sherwood
Keyword(s):  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Reproductive Traits ◽  
Fish Population ◽  
Reproductive Value ◽  
Fishing Pressure ◽  
High Fecundity ◽  
Substantial Impact ◽  
Batch Spawning ◽  
Population Resilience

Abstract Preserving larger fish is often advocated as a conservation measure to help fish populations buffer environmental variation and fishing pressure. The rationale is that several size- and age-dependent reproductive traits confer a higher reproductive value to larger fish. The effects of variation in these reproductive traits on the dynamics of populations under various fishing patterns are however seldom evaluated. In this study, we develop a simulation model to evaluate how variation in three reproductive traits (fecundity–mass, hatching probability, and batch spawning) impacts the capacity of a fish population to withstand and recover from high fishing pressure. Biological functions of the model were calibrated based on the Gulf of Maine Atlantic cod stock, which is currently experiencing its lowest biomass level ever estimated. Results showed that variation in the shape of the fecundity–mass relationship had the most substantial impact on population resistance and recovery. Batch spawning and variation in hatching probability had limited impacts. Furthermore, results showed that preserving larger fish by imposing a slot fishery increased the resistance of the population to high fishing pressure, because it helped preserve the population reproductive potential determined by the high fecundity of large fish. The slot fishery, however, impeded population recovery, because it distributed the fishing pressure on intermediate-size classes which potential for biomass growth is maximal. This study underlines the importance of using precise size-dependent fecundity estimates when evaluating the productivity and sustainability of fisheries, as well as the importance of identifying priority among the components of population resilience (e.g. resistance or recovery) before implementing size-selective harvest strategies.

Modeling shell disease in American lobster (Homarus americanus) as individual-based health trajectories

2014 ◽  
Vol 71 (6) ◽  
pp. 808-813 ◽  
Author(s):  
Michael F. Tlusty ◽  
Anita Kim ◽  
Kathleen M. Castro
Keyword(s):  
Conceptual Understanding ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Molt Cycle ◽  
Health Trajectories ◽  
Human Parasite ◽  
Before And After ◽  
Shell Disease ◽  
Lobster Fishery ◽  
Important Disease

The emergence of epizootic shell disease in American lobsters (Homarus americanus) has presented many new challenges to understanding the interface between disease and the management of the lobster fishery. While a variety of the potentially causative and correlative factors for shell disease have been explored, a clear etiological agent remains elusive. The recency of this disease and the lack of identifiable causal agents have hindered the development of conceptual models that can yield testable predictions. Here, a model originally developed for human–parasite interactions was applied to lobster shell disease as a means to unify the broad experimental and field observations. The model is a graphical means to understand the onset and severity of shell disease and is a function of the length of the molt cycle and the rate of the decrease of health both before and after lesion formation as a function of bacterial abundance and pathogenicity. The model also accounts for shell hardening and passive and active portals of entry for the bacteria. The timing for a conceptual understanding of the epidemiology of shell disease is critical because its prevalence is increasing in key fishing areas. Ideally, such a model will help researchers create hypothesis-driven predictive experiments from which we can further our understanding of an important disease to a critical member of the Gulf of Maine ecosystem.

scholarly journals Evaluating benthic impact of the Gulf of Maine lobster fishery using the swept area seabed impact (SASI) model

2021 ◽  
Author(s):  
Andrew G Goode ◽  
Jonathan H Grabowski ◽  
Damian C. Brady
Keyword(s):  
Gulf Of Maine ◽  
Fish Habitat ◽  
Fishing Effort ◽  
American Lobster ◽  
Fishing Gear ◽  
Marine Habitats ◽  
Small Footprint ◽  
Lobster Fishery ◽  
The Impact ◽  
Swept Area

The Magnuson-Stevens Fishery Conservation and Management Act mandates U.S. fisheries minimize adverse effects of fishing on essential fish habitat (EFH). The Gulf of Maine (GoM) American lobster fishery is the most valuable U.S. fishery, and can deploy more than three million traps annually. To date, the impact of this fishery on benthic EFH has not been addressed quantitatively. To evaluate the impact of the GoM lobster fishery on EFH, lobster fishing effort was incorporated into a model linking habitat susceptibility and recovery to area impacted by fishing gear; the Swept Area Seabed Impact model. Impact to EFH was localized along the coast and highest along mid-coast Maine. Upwards of 13% of the benthos is in the process of recovery, but between 99.92 – 99.96% of initially affected habitat fully recovers. These estimates suggest that lobster fishing negligibly contributes to accumulation of EFH damage in the GoM due to the expansive area fished and the small footprint of each trap. Identifying areas of persistent impact is crucial in developing effective fisheries management for critical marine habitats.

scholarly journals CAN WE STOP THE ATLANTIC LOBSTER FISHERY GOING THE WAY OF NEWFOUNDLAND’S ATLANTIC COD? A PERSPECTIVE

2011 ◽  
Vol 46 (2) ◽  
Author(s):  
Christopher J. Corkett
Keyword(s):  
Atlantic Cod ◽  
Regulatory Policy ◽  
A Priori ◽  
Analytic Approach ◽  
Atlantic Canada ◽  
Increasing Trend ◽  
Lobster Fishery ◽  
Over Time ◽  
The Way

The cod and lobster fisheries of Atlantic Canada are managed in verydifferent ways. Regulatory policy for Atlantic cod has traditionally beenbased on population or biomass measurements, something that has neverbeen done for the management of Atlantic Canada’s lobster. While thesetraditional methods differ, an alternate logical or analytic approach tomanagement is perhaps one way that sound and rational fisheries can bemanaged. The recommendations that follow derive from asking: can welearn analytic lessons from the collapse of Atlantic cod that might allow usto avoid a similar collapse in Atlantic lobster? A landings-per-unit-of-effort(LPUE) index could be constructed for the lobster industry that wouldprovide a continuous trend over time. This trend would form an effectivefeedback model; a declining trend over time would indicate the goal ofsustainability was in jeopardy, whereas a level or increasing trend overtime would indicate that the industry was maintaining its sustainability.Crucially, an LPUE index should only be used as an argument a posterioriinvolving feedback in the form of trends. This index should never be usedas an argument a priori to estimate lobster abundance or lobster biomass

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