Fish­ing link

The Beacon (Gander) - - Editorial -

“The knee-bone’s con­nected to the thigh­bone…” — from the spir­i­tual “Dem Bones”

Some­times, it’s read­ing be­tween the lines that’s most in­ter­est­ing.

In re­cent months, there’s been greater fo­cus on de­clin­ing shrimp stocks and the ef­fect that re­turn­ing cod num­bers might be hav­ing on that de­cline.

You could, of course, jump right to the con­clu­sion that grow­ing num­bers of cod, as shrimp preda­tors, are the whole is­sue.

Not re­ally. After all, cod has a right­ful place in the ecosys­tem. Con­sider this, from the lat­est DFO sci­ence re­port on shrimp stocks: “Pre­da­tion on shrimp, and the as­so­ci­ated pre­da­tion mor­tal­ity rate, showed an in­creas­ing trend un­til 2011, and has de­creased since. This de­crease is as­so­ci­ated with an in­crease in con­sump­tion of capelin by preda­tors in con­junc­tion with the com­bined biomass of shrimp preda­tors re­main­ing rel­a­tively steady since 2011. Shrimp is an im­por­tant for­age species, par­tic­u­larly when there is scarcity of high en­ergy prey such as capelin.”

So, is the is­sue with shrimp a mat­ter of too many cod, or too few caplin?

“The ra­tio be­tween pre­da­tion and shrimp biomass is a rel­a­tive index of pre­da­tion mor­tal­ity and is cur­rently around dou­ble the level in the mid-1990s and 2000s. Shrimp pre­da­tion mor­tal­ity in the near fu­ture is ex­pected to re­main high un­less abun­dance of al­ter­na­tive prey in­creases,” the re­port says.

Over to you, caplin.

Caplin stock as­sess­ments used to be done ev­ery year — then, the span stretched to ev­ery two years. The last one, in 2015, pointed out that, al­though num­bers were strength­en­ing, fish stom­ach con­tents in­di­cated they were hav­ing a dif­fi­cult time find­ing food.

“Given the poorer en­vi­ron­men­tal and feed­ing con­di­tions seen in 2014, cou­pled with the be­low av­er­age strength of the 2014 lar­val co­hort, and the im­por­tance of capelin as a for­age species, it is sug­gested that a cau­tious ap­proach to in­creas­ing to­tal al­low­able catches be adopted,” the re­port said.

Caplin sci­ence is al­ready pretty thin on the ground: it’s fair to say that there’s plenty we don’t know about the im­por­tant lit­tle fish.

The Stand­ing Com­mit­tee on Fish­eries has rec­om­mended DFO go back to an­nual sur­veys, but that’s not re­ally enough. It’s like try­ing to put to­gether a puz­zle with­out hav­ing the pieces.

The re­port on shrimp points out that stock as­sess­ment has to be based on more than “how much can we safely catch?” — the cur­rent fish­eries man­age­ment struc­ture.

“For ecosys­tem-based man­age­ment … ‘har­vest’ would be re­placed by some com­bi­na­tion of har­vest and ecosys­tem func­tion,” the re­port says.

Newspapers in English

Newspapers from Canada

© PressReader. All rights reserved.