A growing number of anglers and watermen have been voicing their concerns about the status of the Atlantic striped bass resource. The recent decline in abundance is in large part due to reduced juvenile production in the Chesapeake Bay. From 2004-2010 the Chesapeake did not produce particularly strong year classes; in fact, the majority of the young-of-the-year (YOY) production during this period was below average. This has created a void in the age distribution of 2 to 6 year old fish. Striped bass take on average six years to grow to the 28″ recreational minimum size, and eight years on average to reach the 34″ commercial minimum size. It should also be noted that only one year class born recently in the Chesapeake was poor enough to qualify as a “recruitment failure”. Under the interstate management plan it takes three consecutive years of recruitment failure to trigger management action.
This trend of lower juvenile production indicates a change in one or more of the conditions that favor the addition of YOY striped bass to the population. Insufficient production of eggs does not appear to be the culprit, as the biomass of reproductively mature females has remained high due to the continued aging and growth of the strong year classes born in the 1990s and early 2000s (Fig. 1, right: Total, spawning stock, and age 8+ biomass (metric tons) of striped bass estimated from 1982-2010. Source: Atlantic States Marine Fisheries Commission). Estimated fishing mortality rates on both juvenile and adult fish are also low, meaning that overfishing is not the reason behind the abundance decline. Rather, the stock is experiencing poor larval survival in the Chesapeake area, which is likely being caused by environmental factors, such as plankton availability, water quality and weather. Most of the striped bass caught by Massachusetts fishermen are spring migrants from the Chesapeake area that feed here during summer and then return to the Bay area in fall. Our striped bass fisheries have thus felt the consequences of the Bay’s poor larval survival in terms of reduced availability of smaller fish (Fig. 2, below, Young-of-the-year relative abundance index for Chesapeake Bay. Source: Maryland Department of Natural Resources).
While Massachusetts commercial and recreational harvest have not declined yet, we can expect the void in age 2 to 6 fish to manifest into reduced recreational and commercial harvest opportunities in the near future. Coast-wide recreational harvest did decrease 27% between 2006 and 2010 (with coast-wide catch dropping 71%). These conditions have led some anglers to recall the stock’s previous crash and draw parallels to today’s fishery. However, there are a great number of differences concerning the stock and its management between then and now. Today’s resource condition is much better than when striped bass stocks became depleted in the mid- to late-1970s. Then, catches of large (and small) fish went virtually uncontrolled at the same time that YOY production was plummeting. The combination of successive years of low YOY production, high fishing mortality, and a much reduced spawning stock biomass caused drastic reductions in catch and harvest levels. Now the stock is closely monitored and managed with much more restrictive regulations, resulting in a rebuilt resource. However, the decline in stock abundance is real and has ramifications for future harvest levels.
The most recent results from the Chesapeake Bay are promising. The 2011 juvenile abundance indices from Maryland and Virginia are ranked in the top-five all time for the survey histories. While this information is encouraging, it must be noted that here in Massachusetts we will have to wait several years before those fish migrate and become a part of our fishery.