Beginning in 2017, IPHC Regulations require that all commercial Pacific halibut must be landed and weighed with their heads attached for data reporting purposes (fish ticket – USA, validation record – Canada) and be subject to the 32-inch minimum size limit. The only exception to this requirement is that vessels that freeze Pacific halibut at sea may possess and land their frozen fish with the head removed and subject to the 24-inch minimum size limit. This regulation change will reduce a recently identified bias in commercial landing data.

In 2013, the IPHC staff began a study to evaluate the relationship used to convert Pacific halibut head-on weight to head-off weight. Collection of these data was integrated into all commercial catch sampling in 2015. For Pacific halibut with heads removed during processing, the weight of the head (as a percentage of the whole body) has historically been assumed to be 10%. However, results from this study indicate that the average current head weight removed is around 12%, with a range from 9 to 18% among different ports and Regulatory Areas1. The range comes from variation in how the head cut is made. Cutting larger heads than the assumed value and reporting weights after these cuts are made have management implications. This practice reduced the estimated landed net weight allowing more individual fish to be harvested within the catch limits. Landing records show that, coastwide, 67-71% of catch by weight is reported head-off, so the potential effect of head proportions that differ from assumed values is substantial and is likely to have a significant impact on the stock assessment. For example, in recent years we may have underestimated the coastwide landings by 2-3%, with some individual Regulatory Areas more inaccurate than others. An example of differing head cuts and the resulting data is illustrated in the table on the next page.

Regulations for the commercial fisheries require the scale weight of Pacific halibut at the time of offloading to be reported on the landing record (fish ticket – USA, validation record – Canada) with the delivery condition code. When the fish ticket notes that the fish were weighed with the head on, reporting systems apply a 10% deduction for the weight of the head.

Head on/off diagram

In order to improve the accuracy of estimated landings, the Commission implemented regulations requiring all commercial Pacific halibut in all IPHC Regulatory Areas to be landed and weighed with their heads attached for data reporting purposes and to only be subject to a 32-inch minimum size limit. An exemption was agreed upon whereby vessels that freeze Pacific halibut at sea may land their frozen fish with the head removed and remain subject to a 24-inch minimum size limit only.

The regulation is detailed in section 13(2) of the 2017 IPHC regulations:

No person on board a vessel fishing for, or tendering, halibut shall possess any halibut that has had its head removed, except that halibut frozen at sea with its head removed may be possessed on board a vessel by persons in Areas 2B, 2C, 3A, 3B, 4A, 4B, 4C, 4D, and 4E if authorized by Federal regulations.

Finally, for Pacific halibut landed with the head intact, the IPHC’s definition of net weight in IPHC Regulation Section 3(l) did not change and continues to include a 10 percent deduction to convert head-on to head-off weight. This calculation occurs automatically in the fish landing receipt system in Canada and the USA depending on the product condition code reported.

For any questions or comments on the new head-on requirement, please contact Jamie Goen at 206-552-7666.