Tuesday, January 5, 2016

Not Enough Menhaden for the Bay's Stripers

The results of a new workshop suggest that Chesapeake Bay foodwebs have shifted as Menhaden (The Most Important Fish in the Sea) have become less abundant in the Bay in recent years, and that Striped Bass are the predator fish most likely to be affected.

You go, girls!
Predators weren’t eating menhaden because there weren’t enough out there
. . . The workshop analysis used the most extensive predator diet data available for the Bay, so the results are solid. What was not made clear in the article, however, is that the data was all collected since 2002, so it only represents current Bay predator/prey relationships. Also not mentioned, menhaden recruitment to the Bay (annual production of young menhaden that are most eaten by predators) has been very poor for the last 20 years. And, a recent scientific assessment of the menhaden population found their numbers coastwide to be near an all-time low. So, to those concerned about menhaden fulfilling their forage role in the Bay food web, the workshop results are not surprising at all — in fact, they bear out the concern that fewer menhaden are being eaten by predators, and some, like striped bass, are being forced to turn to alternative prey — anchovies, blue crabs and baby seatrout — causing other problems.
I've seen a stripers with a belly full of hard crabs this year. But I've also seen them chowing down on huge schools of peanut bunker (small menhaden)
So, are today’s forage dynamics different from earlier, more stable Bay conditions? Where historical predator diet data are available, the answer is yes, at least for striped bass. Several past diet studies were analyzed in a recent scientific journal article that concluded that striped bass prey consumption in the Bay “changed dramatically” between 1955 and 2001. Menhaden consumption declined 10 to 15 times from what it was in the 1950s, when menhaden numbers were at more normal levels. And, as might be expected, anchovies and blue crabs were relatively uncommon in stripers’ diets back then.
It's really time to cut back on the Menhaden reduction fishery to protect the rest of the ecosystem. What point is having a clean Bay if it's devoid (or at least depauperate) of two of it's most important species.

Wombat-socho has "Rule 5 Sunday: Teenage Wasteland" ready at The Other McCain.

No comments:

Post a Comment