scholarly journals Where, when, and which? The importance of heterogeneity in fishery and population processes for the Gulf of Maine stock of Atlantic cod (Gadus morhua)

2021 ◽  
Author(s):  
Micah J. Dean
Keyword(s):  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Population Processes

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 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.

Advances in Fish Tagging and Marking Technology

2012 ◽  
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Stock Assessment ◽  
Stock Identification ◽  
Quality Of Data ◽  
Mark Recapture ◽  
International Industry ◽  
Research Initiatives

<i>Abstract</i>.—In the Gulf of Maine region, Atlantic cod <i>Gadus morhua</i>, are managed as three separate stocks: in U.S. waters, the Gulf of Maine (5Y) and Georges Bank (5Z) stocks and in Canadian waters, the Bay of Fundy stock (4X). The Northeast Regional Cod Tagging Program (NRCTP), a large-scale, international collaborative tagging program, was initiated in 2003 and provides the first region-wide, international snapshot of cod movements, mixing, and growth across all three management areas. As the 2008 stock assessment of Atlantic cod was approaching, these mark–recapture data (114,473 tag releases and >6,500 recaptures) were being analyzed for stock identification purposes. Analysis of raw and weighted data indicate exchanges between different areas which are likely related to spawning behavior, maturation, and environmental conditions. Two core assumptions when defining a stock are that (1) the stock is self-sustaining and that (2) neighboring stocks exist in isolation; the migration patterns observed in the current study may substantially violate both assumptions. With additional ongoing assessments into spatial variation in key life history characteristics of growth and natural mortality, the NRCTP exemplifies the role of conventional mark–recapture data in the complex process of stock identification. The geographic scale and quality of data collected during the NRCTP also confirm the value of international, industry-science collaborative research initiatives; involving this data in both stock assessments and future management initiatives is rewarding to the ~250 commercial and recreational fishermen who tagged cod for this program.

Using acoustic telemetry to observe the effects of a groundfish predator (Atlantic cod, Gadus morhua) on movement of the American lobster (Homarus americanus)

2013 ◽  
Vol 70 (11) ◽  
pp. 1625-1634 ◽  
Author(s):  
Marissa D. McMahan ◽  
Damian C. Brady ◽  
Diane F. Cowan ◽  
Jonathan H. Grabowski ◽  
Graham D. Sherwood
Keyword(s):  
Home Range ◽  
Behavioral Response ◽  
Acoustic Telemetry ◽  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Homarus Americanus ◽  
American Lobster ◽  
Habitat Area ◽  
Predation Rates

American lobster (Homarus americanus) landings have more than quadrupled in the last two decades (1990–2010), coinciding with the collapse of Gulf of Maine groundfish fisheries such as Atlantic cod (Gadus morhua). Recently there has been speculation that the release of lobster from predatory control may have resulted in both lower predation rates and increased foraging areas. We used fine-scale acoustic telemetry within a 200 m × 250 m field enclosure to test the hypothesis that cod induce lobsters to decrease movement and seek refuge. We found a large amount of variation in the behavioral response of individual lobsters to predators; however, the addition of cod into the enclosure reduced maximum daily home range area and significantly reduced the distance traveled from shelter habitat area for all individuals. When predators were removed from the enclosure, lobsters responded by increasing home range area and significantly increasing the distance traveled from shelter habitat area. These results represent the first experimental evidence for American lobster range contraction and subsequent expansion in the presence and absence of cod, respectively.

Interpopulation differences in growth rates and food conversion efficiencies of young Grand Banks and Gulf of Maine Atlantic cod (Gadus morhua)

2000 ◽  
Vol 57 (11) ◽  
pp. 2223-2229 ◽  
Author(s):  
Craig F Purchase ◽  
Joseph A Brown
Keyword(s):  
Growth Rates ◽  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Food Conversion ◽  
Life History Variation ◽  
Grand Banks ◽  
In The Wild ◽  
Conversion Efficiencies

Geographically separated Atlantic cod (Gadus morhua) stocks in the northwest Atlantic exhibit life history variation and have been shown to differ genetically. The genetic and environmental contributions to phenotypic differences, however, have not yet been measured. We used common environment experiments to evaluate the importance of temperature on the observed growth variation between Grand Banks (GB) and Gulf of Maine (GOM) cod stocks. Larvae from the GB grew faster than GOM larvae at both 7 and 12°C. Growth rates of juveniles were not different, but GB juveniles had higher food conversion efficiencies than those from the GOM (at both ambient and warm temperatures). The results indicate that faster growth of GOM cod in the wild is not due to a higher genetic capacity for growth rate in GOM than in GB fish. The findings give evidence of genetically based phenotypic variation, which is in agreement with molecular studies on population differentiation in cod, and support the theory of countergradient variation in growth rates of larval fish.

Residency of adult Atlantic cod (Gadus morhua) in the western Gulf of Maine

2008 ◽  
Vol 91 (2-3) ◽  
pp. 123-132 ◽  
Author(s):  
W. Huntting Howell ◽  
Michael Morin ◽  
Nathan Rennels ◽  
David Goethel
Keyword(s):  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod

scholarly journals Stock identification of Atlantic cod (Gadus morhua) in US waters: an interdisciplinary approach

2014 ◽  
Vol 71 (6) ◽  
pp. 1490-1506 ◽  
Author(s):  
Douglas R. Zemeckis ◽  
David Martins ◽  
Lisa A. Kerr ◽  
Steven X. Cadrin
Keyword(s):  
Population Structure ◽  
Gadus Morhua ◽  
Management Practices ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Biological Information ◽  
Composition Analysis ◽  
Georges Bank ◽  
Biological Population ◽  
Bank Stock

Abstract Mismatches between biological population structure and management unit boundaries often violate the unit-stock assumption, which can reduce the accuracy and relevance of stock assessment results and lead to ineffective fishery management. Since 1972, Atlantic cod (Gadus morhua) have been managed in US waters as two units: the Gulf of Maine and the Georges Bank stocks, both of which have experienced recent difficulties in rebuilding. An interdisciplinary review of available biological information was conducted to investigate cod population structure in US waters and to evaluate the biological appropriateness of the current two-stock model. Our review demonstrates that spawning components in the Great South Channel, Nantucket Shoals, southern New England, and Middle Atlantic are more connected with spawning components in the Gulf of Maine than on eastern Georges Bank, with which they are currently managed. Therefore, a modification of current stock boundaries is recommended to provide a more accurate representation of biological population structure. Proposed alternatives divide inshore and offshore spawning components into separate management units, thereby separating the current Georges Bank stock longitudinally. Continued research, including stock composition analysis, is required to evaluate uncertainties, delineate biological stocks, and develop sustainable management practices that account for intrastock diversity (e.g. winter and spring-spawning components that overlap spatially).

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