Density-independent and density-dependent factors affecting spatio-temporal dynamics of Atlantic cod (Gadus morhua) distribution in the Gulf of Maine

Abstract Due to strong spatial interplays between intraspecific interactions and environmental forcing, both density-dependent and density-independent processes can affect spatio-temporal dynamics of fish populations in a spatially explicit fashion. To this end, this study investigated the underlying mechanisms of spatio-temporal dynamics of Atlantic cod (Gadus morhua) in the Gulf of Maine (GoM). Based on the data from the Northeast Fisheries Science Center (NEFSC) bottom-trawl surveys in spring and fall from 1982 to 2013, empirical cumulative distribution function (ECDF) curves and geographic distribution indices were used to examine the species–environment and abundance–occupancy relationship, respectively. Then, a variable-coefficient generalized additive model was constructed to quantify the simultaneous effects of environmental variables and population size on the spatio-temporal dynamics of cod distribution. Area occupied remained relatively high through the late 1990s, but underwent a pronounced contraction into the western GoM (WGoM) for the reminder of the time-series. The model results suggest that the spatio-temporal dynamics of GoM cod have been driven by complex interactions of density-dependent and density-independent factors over the past three decades. Better knowledge of these dynamics can improve our understanding of the causality of abundance–occupancy and species–environment relationships and help to reduce error estimates for survey-based indices.

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Evaluating spatio-temporal variability in the habitat quality of Atlantic cod (Gadus morhua) in the Gulf of Maine

Fisheries Oceanography ◽

10.1111/fog.12188 ◽

2016 ◽

Vol 26 (1) ◽

pp. 83-96 ◽

Cited By ~ 8

Author(s):

Lisha Guan ◽

Yong Chen ◽

James A. Wilson

Keyword(s):

Habitat Quality ◽

Temporal Variability ◽

Gadus Morhua ◽

Gulf Of Maine ◽

Atlantic Cod ◽

Spatio Temporal

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Identifying the distribution of Atlantic cod spawning using multiple fixed and glider-mounted acoustic technologies

ICES Journal of Marine Science ◽

10.1093/icesjms/fsz064 ◽

2019 ◽

Vol 76 (6) ◽

pp. 1610-1625 ◽

Cited By ~ 9

Author(s):

Douglas R Zemeckis ◽

Micah J Dean ◽

Annamaria I DeAngelis ◽

Sofie M Van Parijs ◽

William S Hoffman ◽

...

Keyword(s):

Gadus Morhua ◽

Fishery Management ◽

Gulf Of Maine ◽

Atlantic Cod ◽

Temporal Distribution ◽

Management Actions ◽

Spawning Site ◽

Management Measures ◽

Fish Spawning ◽

Spatio Temporal

Abstract Effective fishery management measures to protect fish spawning aggregations require reliable information on the spatio-temporal distribution of spawning. Spawning closures have been part of a suite of fishery management actions to rebuild the Gulf of Maine stock of Atlantic cod (Gadus morhua), but difficulties remain with managing rebuilding. The objective of this study was to identify the spatial and temporal distribution of cod spawning during winter in Massachusetts Bay to improve our understanding of cod spawning dynamics and inform fisheries management. Spawning was investigated in collaboration with commercial fishermen during three winter spawning seasons (October 2013–March 2016) using acoustic telemetry and passive acoustic monitoring equipment deployed in fixed-station arrays and mounted on mobile autonomous gliders. Tagged cod exhibited spawning site fidelity and spawning primarily occurred from early November through January with a mid-December peak and some inter-annual variability. The spatial distribution of spawning was generally consistent among years with multiple hotspots in areas >50 m depth. Current closures encompass most of spawning, but important areas are recommended for potential modifications. Utilizing multiple complementary technologies and deployment strategies in collaboration with commercial fishermen enabled a comprehensive description of spawning and provides a valuable model for future studies.

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Faculty Opinions recommendation of Spatio-temporal dynamics of density-dependent dispersal during a population colonisation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.735000428.793556902 ◽

2019 ◽

Author(s):

Donald DeAngelis ◽

Bo Zhang

Keyword(s):

Temporal Dynamics ◽

Density Dependent ◽

Spatio Temporal ◽

Density Dependent Dispersal

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

Journal of Experimental Biology ◽

10.1242/jeb.204.1.157 ◽

2001 ◽

Vol 204 (1) ◽

pp. 157-164 ◽

Cited By ~ 3

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.

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2018-0151 ◽

2019 ◽

Vol 76 (6) ◽

pp. 937-949 ◽

Cited By ~ 1

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.

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0489 ◽

2014 ◽

Vol 71 (9) ◽

pp. 1349-1362 ◽

Cited By ~ 21

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.

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

ICES Journal of Marine Science ◽

10.1093/icesjms/fsw058 ◽

2016 ◽

Vol 73 (9) ◽

pp. 2342-2355 ◽

Cited By ~ 20

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.

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Increased natural mortality at low abundance can generate an Allee effect in a marine fish

Royal Society Open Science ◽

10.1098/rsos.140075 ◽

2014 ◽

Vol 1 (2) ◽

pp. 140075 ◽

Cited By ~ 10

Author(s):

Anna Kuparinen ◽

Jeffrey A. Hutchings

Keyword(s):

Population Dynamics ◽

Population Growth ◽

Density Dependence ◽

Gadus Morhua ◽

Allee Effect ◽

Population Regulation ◽

Atlantic Cod ◽

Adult Mortality ◽

Natural Mortality ◽

Density Dependent

Negative density-dependent regulation of population dynamics promotes population growth at low abundance and is therefore vital for recovery following depletion. Inversely, any process that reduces the compensatory density-dependence of population growth can negatively affect recovery. Here, we show that increased adult mortality at low abundance can reverse compensatory population dynamics into its opposite—a demographic Allee effect. Northwest Atlantic cod ( Gadus morhua ) stocks collapsed dramatically in the early 1990s and have since shown little sign of recovery. Many experienced dramatic increases in natural mortality, ostensibly attributable in some populations to increased predation by seals. Our findings show that increased natural mortality of a magnitude observed for overfished cod stocks has been more than sufficient to fundamentally alter the dynamics of density-dependent population regulation. The demographic Allee effect generated by these changes can slow down or even impede the recovery of depleted populations even in the absence of fishing.

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