October 21, 2012 — Point Nine. Yes, you read it right, as in a tick below one, hovering Alex Rodriguez territory. That’s the number state biologists pegged on this year’s Maryland juvenile striped bass survey (Young-of-Year Index), making this year the lowest in the survey’s 59-year history. The long-term average is 12.
At first blush the 2012 YOY might cause heartburn over the future health of the rockfish stock, arguably the most popular gamefish in Maryland and a top prize throughout its range on the Atlantic coast. Virginia released its survey this week that found similarly poor results, also on the heels of a strong 2011 class
But lets not get ahead of ourselves; there are lots of rockfish in the bay. Wild swings in spawning success are not unheard of, fishery experts say. Specifically, this year’s YOY index was the result of a warm winter and dry spring which created unfavorable conditions for spawning rockfish, according to Eric Durell, Maryland Department of Natural Resources’ point man on the striper survey project. Makes sense, especially when you look at the spawning rates of other fish that use the same waters to reproduce.
So how does this impact the average Chesapeake fishermen who simply wants to fish for fun and occasionally catch dinner? Probably not much, in the short term. If you’re dialed in to the rocks's movements (read: fish two or more days a week) my guess is you have little trouble getting your limit of two legal stripers (18 inches or longer). Yet if you fish just a couple times a month, I bet it’s considerably harder, at least lately.
Let’s open the aperture a bit. It was only a year ago when state fishery biologists recorded one of the strongest indices ever – 34.6. We're eleven years removed from the second-highest mark of 50.8. Since 2006, however, only two-year classes – ’07 and ’11 – registered above the long-term average.
Perhaps more importantly, coastal rockfish have a bull’s eye on them, and face year-round pressure from sport fishermen and watermen alike. Word of a hot bite is just a text away. That wasn’t the case ten years ago, at least not nearly as intensely. Poor water quality in parts of the Chesapeake continues to hamper stripers as well as other marine life.
Also critical to the striper stock’s health is adequate food, principally menhaden. For year fishermen and fishing conservation groups have argued that too many adult menhaden are being harvested from the Chesapeake, and as a result a significant percentage of the rockfish population suffer disease and malnourishment. On Dec. 14, that tide may turn when the Atlantic Menhaden Management Board meets in Baltimore. They can finalize proposed rules governing menhaden harvest that should result in more bunker in the bay and along the coast. That would benefit not only stripers but myriad of other gamefish and sea birds.
Read the full story in the Capital Gazette
Analysis: The article, “Outdoors: Rock survey records all-time low” in the Capital Gazette, alleges that the current rate of menhaden fishing is having a negative impact on predator fish species, such as striped bass, even though the science behind these claims is inconclusive at best. For example, the article claims that a lack of menhaden caused the spread of disease in striped bass. The specific disease to which the article makes reference is mycobacteriosis, a bacterial infection that is currently present in approximately 76 percent of the Chesapeake Bay striped bass population, according to the Virginia Institute of Marine Science.
A 2009 study by Dr. David T. Gauthier in The Veterinary Journal reviewing the available scientific literature concluded that there is currently no consensus about the primary cause of mycobacteriosis, and it is not known which of several potential factors has the greatest influence. However, like much of the Bay’s current ecological problems, environmental degradation from nutrient runoff is likely to play a key role. Excess nitrogen and other nutrients that enter the Bay from sources such as agriculture and urban development lead to algal blooms, the excessive growth of phytoplankton and algae. When these blooms die off, the process of decay consumes the oxygen in the surrounding water, creating hypoxic (low oxygen) areas. These hypoxic areas are usually in deeper, cooler waters, which bass inhabit during the summer. But because the hypoxic conditions make them uninhabitable, the bass are forced into shallower, warmer waters for which they are not ideally suited. The sub-optimal temperature makes them unable to feed properly, and makes them more susceptible to disease. This phenomenon, known as the thermal niche/oxygen squeeze, was documented in striped bass in reservoirs by Charles Coutant, a scientist now retired from the U.S. Fish and Wildlife Service. Coutant published three scientific journal articles (one in 1988 and two in 1990) describing the same phenomenon for striped bass in the Chesapeake Bay.
Striped bass, despite what the article indicates, are not exclusively reliant upon menhaden for their diet. Striped bass are opportunistic predators, and consume a variety of prey species depending on their availability and location. The 2010 annual report of the Chesapeake Bay Multispecies Monitoring and Assessment Program noted that bay anchovies, small crustaceans, and worms are all significant parts of the striped bass diet, in addition to menhaden. Therefore, Chesapeake Bay striped bass population stability is not solely dependent on menhaden population fluctuations.