I recently sent an E-Mail to Mr Steve Hare - Stock assessment scientist for the IPHC. Below is a limited response to some of the questions asked.
The main question asked was if slot size limits would work for halibut as they have for many other fish. The other question asked was why the charter fleet couldn't help in gathering some of the science data they need to manage the resource. Below is his response. I urge all people that catch halibut to make an appearance at the IPHC meetings. As everyone that fishes Cook Inlet is aware - the number of fish being caught over 100lbs has dropped drastically in the last ten years. These are the brood stock for future generations.
As regards your points below, each of them could be responded to at length. If you attend our Annual Meeting, please feel free to seek me out and discuss them with me. But I will give you a brief response now to each of the questions.
2 As for the size of fish plummeting – that concerns us as well. There are two factors at work – one is the size selective nature of harvesting, but the other is ecological in nature. Since themed 1970s there has been an absolute explosion in the number of flatfish in the Gulf, particularly arrowtooth flounder. Arrowtooth have almost no natural predators (including man) thus their numbers have grown unchecked, whereas halibut numbers have been maintained by commercial and sport fisheries. The biomass of arrowtooth is around five times as large as halibut and all that crowding almost certainly has greatly impacted halibut growth.
- Slot limits are not a panacea. In the short term, they save some larger fish and allow them to survive and spawn. However, one of the consequences of a slot limit is generally an increased harvest rate of fish “inside the slot”. As a consequence , fewer fish survive to grow outside the slot so there really is no saving of large animals.
- Tagging by charter operators would only be of use if it was part of a designed experiment. Very few practical, and especially scientifically valid, conclusions can be drawn from unplanned experiments of that type. We do a great deal of tagging here at the commission and have recorded, and routine use for analysis, information on variability in growth rates – by sex, area, time, etc.
Hope this has been of some help.
Halibut assessment scientist