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.

scholarly journals Climate impacts on the Gulf of Maine ecosystem

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Andrew J. Pershing ◽  
Michael A. Alexander ◽  
Damian C. Brady ◽  
David Brickman ◽  
Enrique N. Curchitser ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Algal Species ◽  
Homarus Americanus ◽  
Climate Impacts ◽  
Clupea Harengus ◽  
Calanus Finmarchicus ◽  
American Lobster ◽  
Surface Salinity

The Gulf of Maine has recently experienced its warmest 5-year period (2015–2020) in the instrumental record. This warming was associated with a decline in the signature subarctic zooplankton species, Calanus finmarchicus. The temperature changes have also led to impacts on commercial species such as Atlantic cod (Gadus morhua) and American lobster (Homarus americanus) and protected species including Atlantic puffins (Fratercula arctica) and northern right whales (Eubalaena glacialis). The recent period also saw a decline in Atlantic herring (Clupea harengus) recruitment and an increase in novel harmful algal species, although these have not been attributed to the recent warming. Here, we use an ensemble of numerical ocean models to characterize expected ocean conditions in the middle of this century. Under the high CO2 emissions scenario (RCP8.5), the average temperature in the Gulf of Maine is expected to increase 1.1°C to 2.4°C relative to the 1976–2005 average. Surface salinity is expected to decrease, leading to enhanced water column stratification. These physical changes are likely to lead to additional declines in subarctic species including C. finmarchicus, American lobster, and Atlantic cod and an increase in temperate species. The ecosystem changes have already impacted human communities through altered delivery of ecosystem services derived from the marine environment. Continued warming is expected to lead to a loss of heritage, changes in culture, and the necessity for adaptation.

Re-evaluating Atlantic cod mortality including lobster bycatch: where could we be today?

2020 ◽  
Vol 77 (6) ◽  
pp. 1049-1058 ◽  
Author(s):  
Robert Boenish ◽  
Yong Chen
Keyword(s):  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Homarus Americanus ◽  
Small Scale ◽  
Stock Biomass ◽  
Stock Assessments ◽  
Spawning Stock ◽  
Assessment Bias ◽  
Related Mortality

Full accounting of fisheries mortality is one of the most tractable ways to improve stock assessments. However, it can be challenging to obtain in cases when missing catch comes from small-scale nontarget fisheries unrequired to report incidental catch. Atlantic cod (Gadus morhua) in the Gulf of Maine (GoM), USA, once served as a regionally important fishery, but has been serially depleted to <5% of historic spawning stock biomass. Recent management efforts to rebuild GoM cod have largely failed. We test the hypothesis that unaccounted bycatch of Atlantic cod in the Maine American lobster (Homarus americanus) fishery is a substantial missing piece in the GoM Atlantic cod assessment. We integrated multiple scenarios of hind-casted discards into the two accepted regional cod assessment models from 1982 to 2016. Incorporation of discards improved the assessment bias for both models (10%–15%), increased estimates of spawning stock biomass (4%), and decreased estimates of fishing mortality (9%). A novel evaluation of longitudinal model bias suggests that alternative modelling approaches or specifications may be warranted. We highlight the importance of accounting for all fishery-related mortality and the need for methods to deliver more comprehensive estimates from both target and nontarget fisheries.

American lobster: persistence in the face of high, size-selective, fishing mortality — a perspective from the southern Gulf of St. Lawrence

2018 ◽  
Vol 75 (12) ◽  
pp. 2401-2411 ◽  
Author(s):  
Michel Comeau ◽  
J. Mark Hanson
Keyword(s):  
Gadus Morhua ◽  
Fishery Management ◽  
Atlantic Cod ◽  
Adult Population ◽  
Homarus Americanus ◽  
Snow Crab ◽  
American Lobster ◽  
High Survival ◽  
Size Limit ◽  
The 1960S

The American lobster (Homarus americanus) population in southern Gulf of St. Lawrence has long been subjected to high exploitation, and yet its population is currently at a high and increasing abundance level. The lobster fishery management is based on effort-control, with a short season, mandatory release of egg-bearing females, and strict enforcement of regulations. Another important factor is the high survival of lobster returned to the water. The combination of a minimum legal size limit and either an upper size limit for females or an effective size limit due to entrance-ring size on the traps has resulted in a slot fishery after which the larger, most fecund animals have low vulnerability to the fishery. These efforts to protect large individuals have had a positive effect on lobster larval production, which may lead to even higher adult population numbers. Comparisons with the management of snow crab (Chionoecetes opilio) and Atlantic cod (Gadus morhua) quota-based fisheries were made to try to explain the different trajectories that these three species’ populations have taken since the 1960s.

Predicting bycatch hotspots based on suitable habitat derived from fishery-independent data

2020 ◽  
Vol 641 ◽  
pp. 159-175
Author(s):  
J Runnebaum ◽  
KR Tanaka ◽  
L Guan ◽  
J Cao ◽  
L O’Brien ◽  
...  
Keyword(s):  
Habitat Suitability ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Management Tool ◽  
American Lobster ◽  
Suitable Habitat ◽  
Climate Conditions ◽  
Suitability Index

Bycatch remains a global problem in managing sustainable fisheries. A critical aspect of management is understanding the timing and spatial extent of bycatch. Fisheries management often relies on observed bycatch data, which are not always available due to a lack of reporting or observer coverage. Alternatively, analyzing the overlap in suitable habitat for the target and non-target species can provide a spatial management tool to understand where bycatch interactions are likely to occur. Potential bycatch hotspots based on suitable habitat were predicted for cusk Brosme brosme incidentally caught in the Gulf of Maine American lobster Homarus americanus fishery. Data from multiple fisheries-independent surveys were combined in a delta-generalized linear mixed model to generate spatially explicit density estimates for use in an independent habitat suitability index. The habitat suitability indices for American lobster and cusk were then compared to predict potential bycatch hotspot locations. Suitable habitat for American lobster has increased between 1980 and 2013 while suitable habitat for cusk decreased throughout most of the Gulf of Maine, except for Georges Basin and the Great South Channel. The proportion of overlap in suitable habitat varied interannually but decreased slightly in the spring and remained relatively stable in the fall over the time series. As Gulf of Maine temperatures continue to increase, the interactions between American lobster and cusk are predicted to decline as cusk habitat continues to constrict. This framework can contribute to fisheries managers’ understanding of changes in habitat overlap as climate conditions continue to change and alter where bycatch interactions could occur.

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.

Effects of turbidity on the reactive distance, search time, and foraging success of juvenile Atlantic cod (Gadus morhua)

2005 ◽  
Vol 62 (9) ◽  
pp. 1978-1984 ◽  
Author(s):  
Justin J Meager ◽  
Turid Solbakken ◽  
Anne C Utne-Palm ◽  
Tina Oen
Keyword(s):  
Visual Cues ◽  
Gadus Morhua ◽  
Chemical Cues ◽  
Atlantic Cod ◽  
Search Time ◽  
Turbid Water ◽  
Reactive Distance ◽  
Negative Effect ◽  
Dark Conditions ◽  
Predation Rates

We investigated the effects of turbidity on the foraging behaviour of juvenile Atlantic cod (Gadus morhua) on mysid prey (Praunus neglectus) in the laboratory. The influence of turbidity on vision and chemoreception was examined by measuring reactive distances and search times to visual, chemical, and visual–chemical prey cues over turbidity levels ranging from 0.4 to 17·m–1 (beam attenuation·m–1). We also compared foraging rates of juvenile cod on mysids in highly turbid water and clear water under well lit and totally dark conditions. Juvenile cod using chemical cues were able to locate mysids from significantly longer distances than when only visual cues were available. Turbidity did not affect reactive distance to chemical cues, and had only a weak negative effect on reactive distance to visual and visual–chemical cues. Search time was variable, but tended to increase with turbidity. Turbidity did not affect predation rates on free-ranging mysids, but predation rates were significantly lower in dark conditions than in well lit conditions. We suggest that juvenile cod use chemoreception in conjunction with vision (at close ranges) to locate prey in highly turbid water.

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.

Sign in / Sign up

Export Citation Format

Share Document