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From: Clinton Duffy
Date: 04-05-08
Time: 12:55
Hi John, I guess my contention is not that there was an inshore population distinct from the deeper water part of the population but that inshore reefs were part of the species normal annual range, and that fishing pressure across all habitats (hapuku are accessible to fishers throughout their entire depth range) has reduced the population to a rump. The consequence of this being that seasonal inshore migrations are no longer evident, even though they may still occur, because the numbers are too low to notice. I concede these migrations may not have occured around Northland but they certainly occured in central and southern NZ.
Far from being an "extraordinary angling feat" fishing species to ecological extinction (as apposed to actual extinction) has been repeated over and over again around the world by fisheries for species with similar life histories (i.e. large groupers and jewfishes).
That hapuku are still found on deep reefs is probably the result of the relative isolation of these habitats (5 miles used to be a long way to go for most recreational fishers), and the fact that they are less extensive than inshore reef systems meaning what is left of the hapuku population is concentrated in a relatively small area. This is probably exaggerated by schooling in hapuku. This type of distribution and behaviour can produce "hyper-stability" in a fishery - i.e. catches remain relatively stable, albeit at lower levels, even though the population continues to decline. In the end catch rates in such fisheries are only maintained by discovery of new grounds.
Almost nothing is known of recruitment to the adult hapuku population or the fishery. It seems likley that pelagic juveniles recruit directly to deep reefs in much the same way as bluenose do (alternatively there may be a schooling demersal phase; trawlers sometimes take big bags of juveniles over soft sediments), and that the fisheries on deep reefs are sustained in this way.
As for the possibility that the hapuku that were found inshore were a distinct "cultural group" or sub-population I guess that is entirely possible. We know from tagging studies on other species that behaviour varies by individual and life-history stage. Some are stay-at-home types and some make extensive migrations (e.g. most blue cod never move more than about 300 m post-settlement while a small proportion may migrate over 100 km; for snapper the situation is almost the reverse). The fishers used to say that hapuku that were taken in shallow water had darker backs, compared to the paler deepwater fish.
Whatever the reality is, current levels of fishing on deep reefs are almost certainly sufficient to prevent hapuku from recovering to the point that they again become a regular sight inshore (I completely agree with you on that). That is the reason I think there aren't big schools of puka at the Knights. That and the fact that the reserve probably isn't big enough to adequately protect a resident/semi-resident population. It would also be naive to think that no fishing for hapuku occurs in the reserve. Dave Abbott filmed a dropline broken off in The Slot at the Pinnacles a few years ago, and I know of at least one boat that has been apprehended in the reserve hauling droplines.
Last changed: 04-May-2008