An international team of researchers including Dr. Leif Andersson, a professor at the Texas A&M College of Veterinary Medicine & Biomedical Sciences (CVMBS), and Minal Jamsandekar, a Ph.D. student in the CVMBS Biomedical Sciences program, have used whole genome sequencing to document 53 herring populations from the Atlantic Ocean and the Baltic Sea.
These data could be used to help set fishing quotas that allow for the sustainable harvesting of genetically defined stocks.
“Current methods are limited to phenotypic data and very few genetic markers,” Jamsandekar said. “This leads to misclassification of herring populations occasionally and leads to overexploitation.”
This research identifies genetic markers that make it possible to better monitor herring populations and avoid overfishing. It is particularly relevant for Andersson, who holds a dual professorship with the CVMBS and Uppsala University in Sweden, where herring are a common protein source in the Scandinavian diet.
The Atlantic herring is one of the most abundant vertebrates on earth and is an important food resource for other fish, seabirds, and sea mammals like the fin whale. The Atlantic herring has been an important food resource for humans since the colonization of Northern Europe many thousands of years ago.
“Overexploitation of herring populations severely affects both economics and environment,” Jamsandekar said. “The most abundant Norwegian spring-spawning herring stock collapsed in the late 1960s due to overexploitation. Pacific herring stocks in Puget Sound in Washington State plummeted 92% from 1973-2012 due to water pollution and infection.
“These changes disturb the zooplankton on which herring feed and the larger birds and fish that prey upon herring, leading to ecological imbalance,” Jamsandekar said. “Overfishing of herring populations also has adverse effects on the development and growth of many countries as herring fishery is critical to the European economy as well as to the economies of some coastal regions in the United States, like Maine and New England.”
Herring are a schooling fish, meaning they migrate in schools where they feed, spawn, and cohabitate in groups of up to an estimated four billion fish. Because of this, they can be caught in fishing nets by the ton and are susceptible to overfishing.
In the past, several stocks of herring have collapsed due to overfishing.
This study, published in eLife, will help secure Atlantic herring as a food resource by identifying clear genetic differences that allow scientists to distinguish between all major stocks of Atlantic herring. This allows scientists to track when and where different stocks spawn and track the populations when they are mixed on shared feeding grounds.
The gene variants identified are composed of a few hundred genes related to genetic adaption for environmental factors such as spawning season, salinity, and water temperature at spawning.
Since some of these gene variants are strongly associated with water temperature at spawning, they may also help scientist predict how global warming will affect fish populations. The prediction is that gene variants common in the southern part of the species distribution will become more common in northern populations.
“Particularly now, with rapid climate change, the rate of extinction is increasing for species that have been around for millions of years on this planet,” Jamsandekar said. “A recent study about the extinction of passenger pigeons indicates that even species with huge populations are not safe in today’s world; hence, understanding the genetic basis of different populations in species and finding ways to protect them is much needed than ever before.”
Characterizing the genetic makeup of Atlantic herring will help to secure their future as a viable food resource for humans and other marine animals. As a historically overexploited resource, informed interventions that prevent the overfishing of these animals are invaluable tools to ensure sustainable exploitation of this fish, which is a must at a Scandinavian Christmas dinner.
Contact Information: Jennifer Gauntt, Director of CVMBS Communications, Texas A&M College of Veterinary Medicine & Biomedical Sciences; firstname.lastname@example.org; 979-862-4216