The tough life of a spot fish
Published January 10, 2011
By now you’ve heard the news about millions of fish recently dying in the Chesapeake Bay. It has been speculated by Maryland’s natural resource professionals that the cause is nothing more sinister than unusually cold December water temperatures. While sources continue to tell you about water temperature records and sing the sad song of poor water quality generally associated with the words “fish kill,” we’d like to highlight the main player in this winter tale, the spot fish.
Spot (Leistomus xanthurus) is the species of fish comprising a vast majority of those recently found dead on our beaches. Although a much more common fish in the vocabulary of our Chesapeake Bay neighbors to the south, these fish are regular visitors to Maryland’s portion of the Bay. Like so many other fish, they migrate into the Bay in the spring when the water starts to get warm to take advantage of abundant food and shelter resources.
Larval (baby) spot head toward nursery habitats like tidal wetlands in the portions of the Bay with higher fresh-water influence. Juvenile fish find abundant food and hiding areas in the tidal salt marshes of the shallow-water tributaries. They will grow to nearly 5 inches in their first year by feasting on the Bay’s bounty (including worms, crustaceans and mollusks) – all while avoiding their predators, like the infamous striped bass.
Once waters begin to cool down in our shallow estuary, these fish should begin migrating south. Some have been known to overwinter in the Bay by finding deeper channels where the water is warmest. Most of us don’t think of fish as animals that can feel the effects of cold temperatures, because, well, they are cold-blooded. But like other marine animals, if fish don’t move fast enough, find adequate shelter or interpret nature’s clues to head out, they take the chance of surviving in an environment that is less than ideal. In fact, some are susceptible to quick or extreme environmental changes and can succumb to cold stress. In this case, their bodies simply can’t function.
It's a tough life for a fish, but this past year was a positive one for the spot. It has been reported that the 2010 juvenile spot fish population numbers in the Bay were fairly high. Late this summer, our underwater cameras caught many of these fish around our floating wetland in Baltimore's Inner Harbor. This is good news, and a significant accomplishment for these fish! From the time they enter the Bay, at about only 1 inch long, they must constantly struggle to find food and shelter and avoid being eaten by larger, predatory fish. As we know now, they must also correctly interpret environmental clues to begin migrating before waters get too cold.
We can help make things a bit better for these fish! We may not be able to change the weather, but we can do our part to improve the survival chances of spot and other Bay residents. We can make sure our wetlands are healthy. We can make small changes in the way we do things at home that will make sure the water entering the Bay from our local streams is clean. We can support our elected officials in their efforts to save this vital resource.
It’s a tough life for fish – let’s do our part to give them a chance!
- Photo courtesy of the Maryland Department of Natural Resources