'Illusion of plenty' masking collapse of 2 key Southern California fisheries

[Croaker Dave]

Scripps-led study finds overfishing of spawning areas, environmental conditions behind collapse of 2 bass species

		IMAGE:Kelp bass represent one of the two most important recreational fisheries off Southern California. Click here for more information.

The two most important recreational fisheries off Southern California have collapsed, according to a new study led by a researcher from Scripps Institution of Oceanography at UC San Diego.
Scripps postdoctoral researcher Brad Erisman and his colleagues examined the health of regional populations of barred sand bass and kelp bass-staple catches of Southern California's recreational fishing fleet-by combining information from fishing records and other data on regional fish populations. Stocks of both species have collapsed due to a combination of overfishing of their breeding areas and changes in oceanographic conditions, the researchers found.
As they describe in the most recent edition of the Canadian Journal of Fisheries and Aquatic Sciences, the researchers say the total amount, or biomass, of each bass species decreased 90 percent since 1980. Yet fisheries catch rates have remained stable for a number of years, even as overall population sizes dropped drastically. This is due, the authors say, to a phenomenon known as "hyperstability" in which fishing targets spawning areas at which large numbers of fish congregate, leading to a misleading high catch rate and masking a decline in the overall population.
"The problem is when fish are aggregating in these huge masses, fishermen can still catch a lot each trip, so everything looks fine-but in reality the true population is declining," said Erisman, a member of the Scripps Center for Marine Biodiversity and Conservation. "So as the true abundance is declining, the fisheries data used to assess the health of the fisheries are not showing that and give no indication of a collapse-this is referred to as 'the illusion of plenty.'"
Erisman says the cod fishery that collapsed in the North Atlantic Ocean is the world's most famous example of fisheries data masking an impending collapse, but other fish stocks in regions where fish congregate to spawn are declining as well.
In order to grasp a clear picture of the true health of the barred sand bass and kelp bass in Southern California, Erisman and his colleagues looked outside fisheries data. They tapped into fish population numbers tracked by power plant generating stations, which are required to log fish entrapments as part of their water cooling systems, and underwater visual censuses conducted by Occidental College since 1974.

		IMAGE:This is Larry Allen, a coauthor of the study, with a barred sand bass. Click here for more information.

The authors acknowledge that both bass species began declining in the early 1980s, a drop other studies have directly linked with a climatic shift in regional water temperatures. But they say fishing impacts exacerbated the declines.
"The combined evidence from this study indicates that persistent overfishing of seasonal spawning aggregations by recreational fisheries brought about the collapse of barred sand bass and kelp bass stocks in Southern California," the authors write in their paper.
"The relationship between catch rate and stock abundance suggests there is an urgent need to incorporate fisheries-independent monitoring to create something sustainable and monitor the fisheries effectively," said Erisman. "While fisheries monitoring remains a key part of management, it is clear that such data alone do not provide an accurate assessment of stock condition."

http://www.eurekalert.org/pub_releas...--op092611.php

[Croaker Dave]

I have no comment on the quality of this bass study.

It's interesting that they mention the atlantic cod fishery. IIRC, it was the continual advancing of commercial fishing technology that enabled the fishery to maintain good fish counts even as they decimated the cod population to almost nothing.

[mazilla]

Sounds like junk science tailored to fit their agenda...the world is full of these types of "studies".

[Ed]

Originally Posted by mazilla

Sounds like junk science tailored to fit their agenda...the world is full of these types of "studies".

All they did was compare historical catch rates since 1980. It is more history than science. Pretty good study by Scripps.

[blitzburgh]

I work for a company that supplies product to THE major home improvement chain in the U.S.. We conduct and/or pay for, study, after study after survey, after survey for various sales purposes. The results we receive from any one of these are always mixed at best. I find it hard to believe they can come to such a assertive conclusion with the massive amount of variables that would come into play in something like this.

[Phatford]

I doubt Scripps would risk their reputation on shaky science... The mention Environment in the beginning article. You can't get a good feel for what all they measured in a few short paragraphs and certainly can't fit 30 years of data on one page.

There is no doubt changes need to be made in my mind, but what kind of fair changes can we help make? Calling every study bad science is not going to help our cause. Pretending we are catching the same quality of fish we used to catch is also bad science or poor memory... ha ha

But it's a damn good thing we have people out there saving the seals... oh wait!

[maui jim]

Surprising no mention of the "Goreacle" .....You think Al would have chimmed in..

[robmandel]

like every "study", there are many variables. I would tend to agree that yes, the fishing has declined over the course of the last thirty years I've been fishing. but then again, that's relative to a few things. certainly I've seen some fishing rebound and improve dramatically, for instance the channel islands in ventura/SB counties.

The authors acknowledge that both bass species began declining in the early 1980s, a drop other studies have directly linked with a climatic shift in regional water temperatures. But they say fishing impacts exacerbated the declines.
"The combined evidence from this study indicates that persistent overfishing of seasonal spawning aggregations by recreational fisheries brought about the collapse of barred sand bass and kelp bass stocks in Southern California," the authors write in their paper.

I'm not going to dispute that the fish stocks are not what they once were. however, the question as to why is different. the tremendous growth of coastal populations and all the crap that gets dumped in the water can't be helpful. also, these fish are very structure oriented and that's been a problem.

look at a study like that (and since I teach economics, one must always be aware of cause vs. effect, and must appreciate the difference) and that means the declining bass populations aren't the "problem" but the result of the problem. since they're at the end part of the chain (figuring that water quality improves kelp, more kelp and plankton, more bait fish, more bait fish, etc.) one has to go back to the beginning. bass populations are an amalgam of the components, not the singular issue.

bottom line is that we have ALWAYS supported sound management, reduced take limits, slot limits, all that. no fisherman wants to fish out the ocean. closing off areas to fishing aren't going to the core of the problem since the declining populations are an end result.

In fact, closing areas will only make the problem worse, as we pointed out at the public hearings. the open areas will get overfished even worse, leaving a greater imbalance between the populated areas. and that still won't solve the other environmental issues that have hurt the fish stocks.

[taggermike]

It's a bit of an apples to oranges thing to compare atlantic cod to sand and calico bass. There is no commercial bass fishery in CA. Only party boat landings record numbers of fish landed (no size, age, or sex data). And the landing's numbers are occationally suspect. Private boaters' part in the fishery is difficult to assess. The spotty creel samples taken at the launch ramps can not give an acurate account of fish taken. You factor in the increase in C&R and the view gets even cloudier. 4 anglers bass fishing for 8 hours with no fish landed looks statisticly like 32 hours of fishing effort for 0 fish. That looks like a serious decline in fish stocks. Except they went to San Clemente Island and caught and released 50 calico bass each. They also mention entrapment in power plant intakes. This is real data of fish killed, but only for fish large enough to get caught in screens or traps. Larval fish passing through the power plant's cooling systems are extreamly difficult to quantify. Landings of sport fish are also subject to conditions way out side of fisheries data. When gas was $5.00 a gallon several summers ago it might have made the data look like catches were down when in accuallity there was simply less fishing pressure on the stocks for that time period. OK, I've gone on enough but these are a few things that can complicate studies of this type. Mike

[Handymansd]

Originally Posted by Phatford

But it's a damn good thing we have people out there saving the seals... oh wait!

It would be interesting to see a study on the tonnage of fish that the overgrown colony of LJ seals and sea lions eat VS. the recreational fishermen in LJ. Hell, I bet the Cormorants would give us a pretty good run for our money in pound per capita comparison.

[dsafety]

I may have a worm's eye view of this subject but it is hard for me to believe that recreational fishing has "decimated" the stocks of Calico's and Sand Bass. We are out there on the water and we see what people catch and keep. It would surprise me if on a given day any more than about 25 of these kinds of fish are killed by recreational fishers off the San Diego coast. Most days the take is probably far less.

I suppose that the party boats with their many clients who just want to take home some sort of trophy regardless of species or size, probably hurt the population a bit. Even if that is the case we are talking about a very large ocean here. While some areas are heavily fished, many habitats likely receive little or no fishing pressure.

On the other hand, Scripps is known for its good science and if they say that the fish stocks have been reduced, I am sure they are right. The important questions are, "what is the real cause?" and "how can the situation be reversed?"

In the unlikely case that recreational fishing is the cause, the solution is simple. Shorten the seasons, reduce the limits or if the situation is dire, go to C&R only for the species proclaimed to be in danger. I think that most recreational fishers would happily embrace such regulations if they were based on reliable scientific data.

I am just guessing but I suspect that the real cause is more likely related to the changes in water temperature, food supplies and/or pollution. Maybe these fish are victims of the exploding seal and sea lion populations that have occurred in the places where these fish typically live and breed.

Just my opinion.

Bob

[GregAndrew]

Here are a few other suspect things that I noticed in the article. Their theory on "Hyperstability" assumes that people were not fishing the spawing grounds before. In the case of Sandbass, I would highly disagree with that assumption. I don't believe for a minute that the biomass has decreased by 90% without a decrease in the catch rate, regardless of where they are being targeted. Also, using data from the intakes of powerplants seems a bit skewed too. The long term effect of a 24/7 intake has to be the reduction of the fish population in the nearby waters. Especially for fish of slow growth rate that don't travel very far in their lifetime like Kelp Bass. It is funny how they dismis "changes in environmental conditions" in less than it's own sentence as a contributing factor.

I agree with Rob, there are a multitude of factors that effect the fish counts. And just like forcasting the weather, nobody is very effective at putting all the pieces together. Is there really far less tuna in the sea the last 2 years than there was 3 years ago, or are environmental factors influencing the counts? I also agree that the most important steps are controlling pollution and creating structure along the SoCal coast. Most of the artificial reefs created along our coast are little more than bumps of sand today.

[DanaPT]

Not as many fish in the water.

It's still fun.