NOAA is both right and wrong about Fluke

[reason162]

Originally Posted by dakota560

Reason appreciate your reply and position. When I look at the data holistically I come to a different conclusion. If climate change were the primary culprit, in my opinion we wouldn't have seen a resurgence in SSB from 1989 to 2002 with a sudden reversal and continued decline ever since. The biomass is there, but it's declining every year and at an accelerated rate. Could climate be effecting egg reproduction, can't rule it out. I'd bet the build up of a winter commercial fishery and the biomass being pounded during the spawn has caused considerably more harm in the reproductive process itself and significantly higher levels of unreported dead discard. These fish years ago once they started migrating off shore went untouched for the most part, today they have no safe haven.

NMFS has tried the same failed approach for the last 20 years to the point they said the stock was rebuilt in I believe '10 or '11 and they're wrong. They've been wrong with their management approach and they're still wrong today. Let's wait and see what next year holds in store with the regulations (going to be a disaster) and what the next stock assessment tells us even with chain sweep technology. Hope I'm wrong but in my opinion we're on the wrong path and managing the fishery to a collapse.

If fluke as a species relies on larger-class females to sustain recruitment, that is the kind of evidence you'd expect to lay blame on rec regs selecting for larger females. So far there is no evidence to that effect, though obviously we can learn much more about the species than we do currently.

I agree that winter dragging on the spawning grounds can have a huge impact, much more so than 18 - 19" rec regs. No fish should be molested during spawn, I am firmly in favor of no Spring tog season in NY for that reason.

The thing with climate change is...unfortunately, its effects on a granular level (impact on fluke for instance) is poorly understood. The data is just so massive, and as you know ecosystems are so complex and intertwined...that drawing firm conclusions as to the how and why isn't yet possible. It could be egg production, it could be juveniles settling on the bottom and not establishing themselves due to lack of plankton/food source, it could be an explosion of hitherto unknown predatory species on juveniles...I think regardless of what else NOAA gets wrong or right, incorporating climate change into their model is absolutely necessary, because it's happening.

Originally Posted by reason162

Dakota, I also read your posts with great interest. I am not dismissing out of hand the sex ratio theory, but there is countering evidence which you do seem to dismiss, that fluke is indeed a particularly steep species and therefore resistant to sex ratio imbalance. I think the Rutgers study will shed light on squaring that circle, but the fact is there might not be a conflict to resolve within those parameters if there are larger forces at play. Climate change would most certainly have an impact on fluke migration/recruitment/abundance, as it does on every species on earth. My assumption is that even if true, whatever effect the sex ratio imbalance is on recruitment, the effects of climate change largely eclipses.

I know I don't need to point out to you the difference between causation and correlation, but for the benefit of the forum: the "perfect inverse relationship" you plot between size regulation and recruitment is firmly in the first camp, and could very well be irrelevant IF the causation lies elsewhere, ie global climate change. I wish you were correct, that fisheries management alone is to blame, or that regulations account for the majority of poor recruitment. If that is the case, the solution is relatively easy.

I'm not of the opinion that 25 - 30 years of very definitive trends and distinct relationships are correlations, I believe they're very much are cause and effect driven. Either way these trends and relationships have existed for too long a period of time to be ignored and not better understood. After all that is the responsibility of fisheries management yes?

[gnuisance]

Both of you guys definitely raise the level of the discourse, that's for sure. I feel like I'm more in a graduate school classroom than an internet forum.

Don't fluke migrate east to west? Does climate change still affect that type of migration? But not as directly? Right now we have warm surface temps but colder temps down deeper, how unusual is this for this time of year? Because of a south wind?

From where I'm sitting it just seems so unfair that commercial fisherman are getting hundreds of pounds of fish in every tow while the rec guys are grinding it out for a couple bites. I don't feel an allegiance to commercial fishing like some guys do.

The DEP came out this year in protection of the fluke fishing industry, both rec and commercial. With the idea being that the reduction would harm the industry. Well here we are 6 weeks later and the party boats are sea bassing and ling fishing and many rec anglers have given up entirely and it's not because we went to a 3 fish limit.

Gnuisance the fluke fishery is essentially an east / west migration. I've always felt based on what I believe your implying that fluke are more prone to stage at different depths east / west to find the water depth they prefer and bait concentrations they need as opposed to a north / south migration but there's a lot that factors into that so that's an assumption. Bait concentrations, currents, water quality, storms (i.e. Sandy) etc. might and probably will impact some level of movement. That's precisely why in the spring the fluke move into the bays where the waters warmer and bait is more prevalent and exit the bays in the summer as the water temperatures increase and move further off shore to deeper water, larger fluke in particular. That point is also covered in Rutgers Sex and Size Study. As I've mentioned, the biomass is there albeit its been declining since 2009 when it was recorded at ~46,000 metric tons. In '15, last year on record, it was ~36,259 metric tons.

A few more statistics directly from NMFS. In 1989 when SSB hit rock bottom at ~7,000 metric tons, the subsequent three years catch as a percentage of SSB were 68%, 108% and 100%. Those are insane catch percentages when SSB was dramatically declining YET after that three year period SSB increased to 12,500 metric tons, an almost 80% increase in three years with significantly higher catch percentages compared to today's ~ 15%. For the last three years on record from NMFS, '13 thru '15, SSB decreased from ~40,000 metric tons to ~36,250 metric tons while catch as a percentage of SSB in those years was reported at 26%, 24% and 21% respectively. The increase between '90 and '92 could be interpreted to Reason's argument that the stock is fecund and "found a way" in light of being at reduced levels. My opinion instead is you can't discuss a stock's recruitment capacity without consideration being given to the gender composition of that biomass. That's what I personally believe to be the biggest flaw with steepness theories and advocates. Say it differently, if SSB was 50,000 metric tons but was comprised of all males and no females, would the future be more promising than an SSB of 10,000 metric tons with a 50 / 50 gender mix. You can't categorize a stock as steep without consideration being given to the gender make up of that stock....period. Not to mention the fact that the data does not support the fluke fishery as being fecund or steep since the biomass has been trending down for 15 years now. The reason SSB increased between '90 thru '92 in spite of extremely high catch percentages relative to overall SSB was recruitment strength was still strong enough to support a sustainable fishery. That all changed over the last 15 years as size limits regulations changed and commercial interests started pounding larger fluke year round, especially during the primary spawn period..

To my initial point, the data tells us the biomass is there, 500% greater than it was in 1989 (36,250 mt's compared to 7,000 mt's), catch has been slashed yet SSB declines. Plot that data against recruitment strength for the same period of time. For the years '90 thru '92, recruitment averaged ~2,900 new fish age zero for every metric ton of SSB, that average crashed to ~675 for the period '13 thru '15. That's a 76% decrease in reproduction for those periods. That is the primary issue killing this fishery.

The million-dollar question is what's causing that decline which NMFS is NOT addressing with the same approach to managing the fishery which is catch reductions thru size limit increases. If you examine the data as I have for 25 years and look at the relationships between a sliding recruitment line directly proportional to an increasing size limit trend line it's hard if not impossible to not believe there is a causal relationship between size limit increases, the effect they have on more female fluke being harvested and the corresponding negative impact on recruitment statistics. There's 25 - 30 years of data to support that conclusion.

One last comment on migration, commercial operators will tell you fluke are being caught in areas north and east of traditional spots which fuels the migration theory. You have to ask the question if true, could that be the case because the biomass is spreading out in certain areas as opposed to a massive change in migratory movements due to climate change. What I mean is look at the quotas, catch level and size limits over the last 10 years by state. A few more statistics. '16 reported results from the ASMFC Draft Addendum catch totals for our area (NJ, NY and Ct.) were 5,466,371 pounds. The northern most states included in the Mid-Atlantic region RI and Ma had a projected harvest of 412,261 pounds, not even 15% of the catch in our immediate area. Size limits in our immediate area have been 18” the last two years, in Ma it was 16” in 2016. Keep in mind that NY in ’09 and ’10 was 2 fish at 21’ and in ’11 it increased to a 3 fish possession limit at 20.5”. No one can emphatically prove it but it begs the questions of whether the appearance of a change in fluke migratory patterns is in actuality the result of lower size limits and greatly reduced possession limits in the northern states of the Mid-Atlantic region combined with an overall harvest level not even 15% of that in the NY Bight. As I said, bait concentrations move, fish swim, storms happen which reshape the ocean’s contour. Do these factors impact yearly migration patterns, you could assume to some degree they might. BUT does it mean there’s a massive wholesale movement of the biomass to northern areas as a result, personally I don’t read the data that way. The biomass was still reported at ~36,250 metric tons in ’15, that tells me the biomass is still where it’s largely been for the last 25 – 30 years. In my opinion if there 's an appearance of the biomass moving north it could just as easily be the result of significantly less harvest in the northern states of the region combined with size and possession limits for those states more protective of the female breeders than in our immediate area. Can't prove that point any more than anyone can prove there's a massive shift in fluke migration taking place.

[Ttmako]

How does climate change impact bottom water temperature?
I know surface temperature of the earth have increased 1.3 degrees in the last century.
Curious to know how that impacts the bottom temperature? I assume it would be something less than 1.3 degrees over the last 100 years.