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Scientific findings concerning Seal's diet

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This is a snippet I took from my piece on Seal's and Great Whites, regarding the dietary habits of our local seal population - as seen in OTW. Hope you guys enjoy (if anyone is interested, I'll let you know the issue):

 

....But, do seals really target striped bass? According to experts from NOAA and the Mass. Division of Fisheries, research is showing differently; and recent surveys by biologists, studying the dietary habits of local grey seals are finding the answers in scat samples and stomach contents. Bone and crystal fragments from the inner ear section of the prey that make up the local seals’ diet are revealing their primary forage does not include striped bass, but rather, the majority of the findings show sandeels as their main source of food throughout the year. Rounding out the menu is hake, followed by flounder, skates, squid and herring, along with the occasional other prey-fish. What does this mean for the local fish stocks? The impact is complex, where the prey of seals can also be a major food source for other fish, including striped bass, such as the case with sandeels; but there is also the impact where seals can be consuming certain species that feed on another, thus allowing one species to thrive while another is depleted. For fishermen, the lack of striped bass in a once, highly productive area, where now it seems the furry heads bobbing up and down in the waves seem to outnumber the Linesides, makes it easy to point the finger at the sea dog’s appetite, presuming that the stripers are the main course, when in reality, it is the lack of sandeels. This leaves the surfcaster with little more than sand on his boots after a long night, plying the surf. And while sandeels are still present inshore; for those of us that have ventured just a bit offshore, there are clouds of sandeels that prefer to remain in the deep. However, seals are opportunistic predators, and for those wayward striped bass that are unfortunate in their decisions of which currents to ride; they will end up in a set of furry jaws if the opportunity arises. Exactly how often they end up as an entrée is hard to figure, as a result of their feeding habits. According to Gordon Waring, for some reason, seals, when targeting a striped bass, seem to prefer the fatty stomach area, ripping the stomach from the fish, so stomach contents do not easily reveal striper remains. The decline in striper catches in inshore waters can not be attributed mainly to the growth in the seal population, as the number of fishermen taking advantage of the recovered fishery spawned numerous new anglers; but clearly the impact is substantial. Whether it is a result of stripers being targeted as a food source, or whether it is the striped bass’ food supply, in the form of sandeels, herring, and squid, being decimated by hungry seals, one thing is certain... The days are growing thin, more a memory, when you could expect fast action at places such as Chatham inlet, where on a cloudy night, drifting a bomber would result in stripers slapping away at your plug until Pleasant Bay ebbed to a crawl. I’ve seen it while wading too, where schools of baitfish would be raining all about, as I quietly parted the water, now being replaced by only the sound of the rippling current. Big fish appear to be staying offshore for longer periods of time, chasing the baitfish that prefer risking the deeper water, rather than the snapping jaws that await near shore. Clearly, frustration is growing among the angling crowd, where a balance is sought to please both fishermen and environmentalists. Gone are the days of bounties; but there may be some checks and balances that can be established to satisfy the majority. There is, however, another player in this equation, one that has yet to fully reveal its’ capability in disrupting whatever level of comfort established. The aforementioned, great white shark.

 

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True - but the lack of bait is a direct result of the seal population in the Chatham inshore area. Lots of bait, big fish offshore, slim pickings in close and up inside.

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This is a snippet I took from my piece on Seal's and Great Whites, regarding the dietary habits of our local seal population - as seen in OTW. Hope you guys enjoy (if anyone is interested, I'll let you know the issue):

....But, do seals really target striped bass? According to experts from NOAA and the Mass. Division of Fisheries, research is showing differently; and recent surveys by biologists, studying the dietary habits of local grey seals are finding the answers in scat samples and stomach contents. Bone and crystal fragments from the inner ear section of the prey that make up the local seals’ diet are revealing their primary forage does not include striped bass, but rather, the majority of the findings show sandeels as their main source of food throughout the year. Rounding out the menu is hake, followed by flounder, skates, squid and herring, along with the occasional other prey-fish. What does this mean for the local fish stocks? The impact is complex, where the prey of seals can also be a major food source for other fish, including striped bass, such as the case with sandeels; but there is also the impact where seals can be consuming certain species that feed on another, thus allowing one species to thrive while another is depleted. For fishermen, the lack of striped bass in a once, highly productive area, where now it seems the furry heads bobbing up and down in the waves seem to outnumber the Linesides, makes it easy to point the finger at the sea dog’s appetite, presuming that the stripers are the main course, when in reality, it is the lack of sandeels. This leaves the surfcaster with little more than sand on his boots after a long night, plying the surf. And while sandeels are still present inshore; for those of us that have ventured just a bit offshore, there are clouds of sandeels that prefer to remain in the deep. However, seals are opportunistic predators, and for those wayward striped bass that are unfortunate in their decisions of which currents to ride; they will end up in a set of furry jaws if the opportunity arises. Exactly how often they end up as an entrée is hard to figure, as a result of their feeding habits. According to Gordon Waring, for some reason, seals, when targeting a striped bass, seem to prefer the fatty stomach area, ripping the stomach from the fish, so stomach contents do not easily reveal striper remains. The decline in striper catches in inshore waters can not be attributed mainly to the growth in the seal population, as the number of fishermen taking advantage of the recovered fishery spawned numerous new anglers; but clearly the impact is substantial. Whether it is a result of stripers being targeted as a food source, or whether it is the striped bass’ food supply, in the form of sandeels, herring, and squid, being decimated by hungry seals, one thing is certain... The days are growing thin, more a memory, when you could expect fast action at places such as Chatham inlet, where on a cloudy night, drifting a bomber would result in stripers slapping away at your plug until Pleasant Bay ebbed to a crawl. I’ve seen it while wading too, where schools of baitfish would be raining all about, as I quietly parted the water, now being replaced by only the sound of the rippling current. Big fish appear to be staying offshore for longer periods of time, chasing the baitfish that prefer risking the deeper water, rather than the snapping jaws that await near shore. Clearly, frustration is growing among the angling crowd, where a balance is sought to please both fishermen and environmentalists. Gone are the days of bounties; but there may be some checks and balances that can be established to satisfy the majority. There is, however, another player in this equation, one that has yet to fully reveal its’ capability in disrupting whatever level of comfort established. The aforementioned, great white shark.

 

This is exactly what I was elluding to in my 'seal observation' thread.

 

I knew years ago sand eels made up the bulk of their diet. I was also told by someone at Woods Hole that seals like to eat fish they can easily attack from above, like skate, flounder, and lobsters. It appears as though the seals have decimated the inshore sand eel population and that's probably why the bass have taken up residence offshore, where the sand eels are relatively safe from them.

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You got it Bob - an old sharpie like you has seen it right before your eyes. we'll see over the next two years. I hear the reports from chesapeake; but i swear if people think this makes a difference over the next 8 years they're huffing paint fumes. we're looking at some jumbo fish here and there but scarce on the schoolie front. this gets into another argument where we should bump up the size for 5 years but whatever.... obviously, you guys know I'm not a canal regular, but I fish it enough to know. My usual haunts are not much further on the south side and up on the outer beaches; but I do enough canal fishing to see it there.

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True - but the lack of bait is a direct result of the seal population in the Chatham inshore area. Lots of bait, big fish offshore, slim pickings in close and up inside.

 

That's horrendously simplistic and very hard to prove or disprove. Your suggesting localized depletion of bait fish by seals is accounting for the lack of bass inshore?

 

Then how do you explain the lack of bass in areas without seals, or off-shore where there is plenty of bait and no bass? Or the decline in bass numbers further north where seals have been in supply all along, but only recently have the bass not been showing up?

 

Do seals have some impact...sure. but while the are the more obvious of predators, the removal of baitfish by even this level of seals is on par with that consumed by predatory fish; particularly dogfish (http://icesjms.oxfordjournals.org/content/64/1/83.full) and certainly well within that natural mortality of the stocks.

 

I've got a more realistic explanation. Fishing. As we all know the most recent stock assessment report was clear that the coast-wide population of bass is ok, but the Chessy (the one that supplies most of N. New England)...isn't doing so well., judging by the recruitment index int he Chesapeake Bay and the increases in harvest during the Chesapeake Bay populations spawning period

 

I think before we start to point fingers and predators, we should be looking to our own fishing, and pattern of fishing as the cause.

 

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MDC - if you see my brief response that you term "horrendous", you'll see I am discussing the Chatham area. Yes, obviously anyone who wets a line knows the numbers are down coast-wide; but this thread relays information passed on to me by scientists who study seals for a living, and focuses on their dietary habits in this area. I believe their answers have a little more weight than speculation.

 

if you don't think the seal's in Chatham and Monomoy are impacting the bait stocks, and then the predators, you are not being realistic.

 

And, while the most recent assessment showed positive results, that is one year; and these fish will not be mature for years - - this comes after years of poor showings.

 

I am in favor of a moratorium, similar to one from the 80's; but there is a problem with an overpopulation of seals in Chatham - fact not opinion!

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