Fish population genomics
Fish are entertaining to watch, fun to catch, and can be delicious to eat. However, uninformed fisheries management strategies that fail to consider population structure can result in severe consequences for reproductive capacity and stock rebuilding. My lab uses genomic data to deepen our understanding of fish population dynamics, with a particular focus on data that will be relevant to conservation and management.
Atlantic Cod
Atlantic cod has been and continues to be an important economic resource in Massachusetts Bay and the Gulf of Maine. Since 2000, Atlantic cod total catch in New England has decreased by approximately 6-fold resulting in a significant economic and ecosystem loss. Cod have been historically thought as a migratory species with little diversity within the stock. Recently this specific view of cod has been expanded, as the existence of different ecotypes in the Gulf of Maine have been described. Spring cod spawn in the springtime and are found in deep water, winter cod spawn in the wintertime and are found in deep water, and red cod are found in shallow water but it is unknown when they spawn.
Currently, we are using genomics to study the genetic differences between ecotypes in the Gulf of Maine and their responses to warming. The Gulf of Maine is warming faster than 99% of the worlds oceans, and is at the southern end of the range of cod. Graduate student Sara Schaal has been also been comparing cod ecotypes from the Gulf of Maine to Iceland to better understand how cod stocks have evolved across their range.
Results from our research will give insight into To improve stock definitions and understanding of stock boundaries.
Collaborators: Jon Grabowski (Northeastern University), Graham Sherwood (GMRI), Lisa Kerr (GMRI)
Graduate students, dreaming about catching cod.
Black Sea Bass
Warming seawater temperatures in the Gulf of Maine has resulted in the northern range of some fishery species to move further northward. One such species that is shifting rapidly is the northern stock of black sea bass, which historically ranged from Cape Hatteras to Cape Cod, but is now common in the Gulf of Maine (GOM). While this range expansion presents a new opportunity for fisheries, it has also been a source of contention because resource managers have struggled to keep pace with rapidly shifting species distributions in New England and other regions globally where coastal seawater temperatures are rising rapidly.
We have recently obtained funding from NOAA to quantify population genetic structure of black sea bass and the fisher perceptions of black sea bass population increases. This information will be crucial to ongoing efforts to manage black sea bass at the northern edge of their range.
In addition, Remy Gatins, a Postdoctoral Fellow with the National Science Foundation, is using this rapid range expansion to test evolutionary predictions of increased deleterious mutation load in the expanded range.
Collaborators: Jonathan Grabowski and Steven Scyphers (Northeastern University), Marissa McMahan (Senior Fisheries Scientist, Manomet), Remy Gatins (Northeastern University)
Pacific Rockfish
Many species of Pacific rockfish (Sebastes spp.) are long-lived (50-100 years) and have high catch-and-release mortality, characteristics that makes it difficult for them to recover from overfishing. Many rockfish species have suffered severe declines since the 1980’s due to fishing, which has spurred several recent management efforts through marine reserves and closures in both the US and Canada. Understanding both how rockfish populations are connected via dispersal and how the reproductive success of rockfish populations depends on the ocean environment is crucial for recovery efforts, however little is still known about these processes in rockfish.
We studied the population dynamics of Sebastes melanops (black rockfish, pictured left) and other rockfish species in Barkley Sound, British Columbia and across the US-Canada border from 2005-2014. We used Standard Measuring Units for the Recruitment of Fish (SMURF’s) and visual surveys to monitor rockfish recruitment. Our previous research has unexpectedly shown that the abundance of recruits was not correlated with the number of parents that produced them. We explained this counterintuitive result by showing how oceanographic processes shaped the reproductive success of adults and survival of larvae (Lotterhos and Markel 2012). In a larger scale study we found that Rockfish Conservation Areas in Canada and the US were largely unconnected by dispersal due to a lack of reserves near the US border (Lotterhos et al. 2014). We have also synthesizing spatial recruitment data with data on adult abundances to test hypotheses about the spatial and habitat drivers of abundance (Lotterhos and Markel 2017), and about the importance of strong year classes for the fishery (Haggarty et al 2017).
Did you know that black rockfish can live to be over 50 years old?