Disentangling the Effects of Climate Change, Exploitation and Predation As Drivers of the Decline of Winter Flounder

Analysis of winter flounder catch data from the New York State Department of Environmental Conservation’s Western Long Island seine and the Peconic Bays trawl surveys show declines in winter flounder abundance over the past two decades with levels near extirpation in several locations.  Survey data indicates an initial period (1990s) of decline of older winter flounder, which corresponded with an increase in the number of YOY recruited per female, suggestive of a compensatory response of increased recruitment productivity.  However, after the early 2000s YOY recruitment dramatically declined, and trends suggest population collapses in several locations.  We evaluated the leading hypotheses of the species’ decline including the following: climate change, exploitation and predation.  Specifically, historical telemetry data shows that fishing mortality was likely well above sustainable levels during the 1930s, 1950s and 1960s and harvest remained high until the 1990s. Analysis of survey data provides correlative evidence that both temperature and predator abundance could be related to the species’ decline.  We present data suggesting that individual condition and growth of YOY are within normal expectations for a healthy population; however, mortality of post-settlement juveniles is higher than historical estimates suggesting low survival of YOY is currently hindering recovery.