American lobster (Homarus americanus) landings have more than quadrupled in the last two decades , 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.Résumé : Les débarquements de homards (Homarus americanus) ont plus que quadruplé au cours des deux dernières décennies , coïncidant avec l'effondrement des pêches aux poissons de fond, comme la morue (Gadus morhua), dans le golfe du Maine. Il a récemment été proposé que la disparition du contrôle des homards par la prédation puisse s'être traduite par des taux de prédation réduits et de plus grandes zones d'alimentation. Nous avons utilisé la télémétrie acoustique de haute résolution dans un enclos en mer de 200 m sur 250 m pour vérifier l'hypothèse voulant que la morue incite les homards à restreindre leurs déplacements et à trouver refuge. Nous avons noté d'importantes variations en ce qui concerne la réaction comportementale individuelle des homards à la présence de prédateurs; cela dit, l'ajout de morues dans l'enclos a entraîné une diminution de la superficie maximum du domaine vital quotidien et une diminution significative de la distance des excursions en dehors de la zone d'habitat refuge pour tous les individus. Quand les prédateurs étaient retirés de l'enclos, la superficie du domaine vital des homards augmentait et la distance des excursions en dehors de la zone d'habitat refuge augmentait significativement. Ces résultats constituent les premières preuves expérimentales de la contraction du domaine vital du homard en présence de morues et de son expansion en leur absence. [Traduit par la Rédaction]
The warming of the world's oceans has resulted in the redistribution of many marine species globally. As species undergo range shifts, the expanding edge of the population often experiences novel environmental and demographic conditions that may result in the emergence of variation in life-history strategies. The northern stock of black sea bass, Centropristis striata, has recently expanded its distribution poleward, into the Gulf of Maine. Management has struggled to keep pace with this rapid range shift, in part, because very little is known about the expanding population. We compared life-history traits of black sea bass collected from 2013 to 2016 from the northern most point of the historic range of the northern stock (southern Massachusetts) to those from two areas in the newly expanded range (northern Massachusetts and Maine). We found significant differences in size, diet, condition, maturity and sex ratio between black sea bass from southern Massachusetts and the Gulf of Maine. Overall, sea bass in the newly expanded range consumed a less diverse diet and their condition was lower, but they reached maturity at a younger age. We also found greater length-and age-at-maturity estimates from all regions combined compared to the most recent black sea bass stock assessment which includes data from Cape Hatteras, NC to southern Massachusetts. This study represents initial observations of life-history traits of sea bass in its newly expanded range in the Gulf of Maine, and suggests that these sea bass exhibit lifehistory strategies that differ from their southern counterparts within their historic range. Given these findings, the stock assessment for the Northeast U.S. Continental Shelf black sea bass stock may not be adequate for sea bass in the Gulf of Maine. Studies investigating the expanding edge of economically valuable fishery species are needed to aid in ongoing and future efforts to assess and manage their stocks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.