Fishing Victoria Forum

It has become clear that climatic variability exerts a powerful effect on the population dynamics of the very large fish stocks that are the basis for the major commercial fisheries of the world (see volumes edited by Beamish, 1995 and Bakun and Broad, 2002). A tendency for multi‐year runs of good or poor recruitments results in a situation wherein the most consequential population variability generally occurs not from 1 year to the next but rather on scales of one to several decades. This tends to make it nearly impossible to confidently separate effects of human interventions (overexploitation, habitat alteration, changes in ecosystem structure, etc.) from natural climate‐related variability.

However, the sudden simultaneous expansions of the Japanese and South American sardine fisheries in the early 1970s to mid‐1980s from near total absence to unprecedented landed tonnages, followed thereafter by simultaneous sudden declines, are certainly remarkable, and appear clearly to be reflective of population increases. And the sudden decline of the Mexican fishery at the same time clearly mirrors the pattern. But what raises the pattern from merely interesting to truly exciting is the fact that many other of the world's largest fish populations, particularly in the North Pacific (Hare and Mantua, 2000; Benson and Trites, 2002) but also in other regions around the world, experienced similar patterns of gyration at the same time (Bakun, 1996; Bakun, 1998).

What they are saying is there is no such thing as a steady state for fisheries regardless of fisheries management. There will be boom and busts in fish stocks. These are controlled by the oscillation of the climate.

referring to the 1970-1980 boom bust.
Indeed, this was a period of particularly steep trends in many climatic index time series. The Southern Oscillation Index (SOI) went through a decadal‐scale decline (Fig. 4) that was much deeper and more extended than had occurred in the previous several decades (the early 1970s to mid‐1980s constituting a sort of decadal‐scale analog to a standard annual‐scale El Niño episode). The Pacific Decadal Oscillation (PDO) exhibited a corresponding decadal‐scale increase (Fig. 4). The Aleutian low pressure cell, that dominates the seasonal behavior of the subarctic Pacific ocean‐atmosphere system, intensified and expanded. Certain other index series exhibited similar features (Klyashtorin, 2001; Chavez et al., 2003). Even global‐scale indices such as the mean air temperature of the earth (Fig. 4) (Kawasaki and Omori, 1988) and the rate of the earth's ‘solid body’ rotation8 also showed particularly steep sustained trends during this period.

In Australia the early part of the 1970s saw Lake Eyre flooded to it's deepest ever recorded and a huge increase in Cyclone activity. So my "normal" turns out to be a rare exception.
The vast amount of Tuna and bait fish around at those times and the lack of them in the 1990 and 2000 is related to ENSO as well as commercial fishing.
It also means that the huge fleets exploiting the Tuna and catching vast amounts may have been doing so at a time of rare large stocks.
This would explain the slow return of tuna stocks despite strong fisheries reductions.
It could possible mean that the increase of them, and related species turning up this last few years is a hint of better climate conditions for them.
All conjecture at this stage but very interesting reading.

Thanks re-tyred.

Seb85 wrote: ↑

Tue May 19, 2020 1:26 pm

Is there a hard copy book of this or something similar?
I'm old school, I like reading hard copy books while commuting and before bed.

Completely right about authors having little say regarding publishers charging to access texts. I didn't get any say when I published as a group, haha.

I unfortunately doubt there would be physical copies since this was published in a volume of the The International Journal of the Japanese Society of Fisheries Oceanography, thankfully through networks I was able to source a full digital copy through the Australian Freshwater Sciences Society. Authors permission to share.

I've uploaded the PDF file via this link Environmental 'Loopholes' and fish population dynamics: comparative pattern recognition with focus on El Nino effects in Pacific

Saw the post by born2fish on a few Facebook fishing groups. Thought it was our old pal Phil unless he has a different boat, put on a few kegs and learnt English he has a competitor with the same name.

rb85 wrote: ↑

Wed May 20, 2020 11:37 am

Saw the post by born2fish on a few Facebook fishing groups. Thought it was our old pal Phil unless he has a different boat, put on a few kegs and learnt English he has a competitor with the same name.

Not ol mate, nothing changed with him.
they did get a small tuna over the last weekend.

purple5ive wrote: ↑

Wed May 20, 2020 2:32 pm

rb85 wrote: ↑

Wed May 20, 2020 11:37 am

Saw the post by born2fish on a few Facebook fishing groups. Thought it was our old pal Phil unless he has a different boat, put on a few kegs and learnt English he has a competitor with the same name.

Not ol mate, nothing changed with him.
they did get a small tuna over the last weekend.

It’s a shame Phil isn’t still here