How old is a 40 pound halibut?

Quick answer: 12. Actually, there is no simple answer to this question. It all depends on the sex of the fish and from which regulatory area it came. Female halibut tend to grow faster, so a 40 pound female would be younger than a 40 pound male. Also, halibut seem to grow faster the farther north(west) you go: a 40 lb fish off the coast of Washington State is likely to be a lot older than a 40 lb fish off of Kodiak I., AK.


Does the length-weight table really work?

According to our scientists, the table is very accurate. Back in 1926, 454 halibut were caught off Masset, B.C. Their fork lengths and weights were measured and a formula was worked out:

WN = 6.921x10-6 x L3.24 , where WN=(head-off, eviscerated wt in pounds) and L=(fork length in cm)

In 1989, Bill Clark looked at the length-weight relationship of 5184 fish caught from B.C. to the eastern Aleutian Islands. Bill found that his data matched very closely with the 1926 formula, which was "higher on average by about 1%, but there is no practical difference..." Like all things in nature, a single halibut's weight can deviate up to 10-20% from the norm; but, taken in a group of say, 20 or more fish, these random errors should cancel out.

The length-weight table is available in centimeters or inches.

If you would like further information, please contact Ian Stewart (206) 634-1838.


Do I need a fishing license from the IPHC?

The IPHC no longer issues licenses for fishing in Alaska or British Columbia. Federal and State permit requirements must still be fulfilled, however.

IPHC licenses are necessary for commercial and sport fishing in Area 2A. License applications are available here.

NOTE: If you made a commercial landing or held an IPHC Sport Charter License last year, you will automatically be mailed a renewal form.


I've caught a tagged halibut...what do I do now?

When the fish is caught, do not remove the tag. If it is caught commercially (when the tagged fish will be mixed in with many other halibut in a hold) tie a rope or gangion around the tail (or through the mouth) so identification will be easier at the time of landing. It should be noted that tagged fish may be retained even if it is undersized (<81.3 cm) or if the fisher does not have the proper permit(s) to fish for halibut.

Once in port, there are a number of things you can do. If you are in Bellingham WA, Homer AK, Juneau AK, Kodiak AK, Petersburg AK, Port Hardy BC, Prince Rupert BC, Seward AK, Sitka AK, or Vancouver BC, the best thing to do is track down the Commission Port Sampler. Local fisheries offices should know how to get in touch with them (or contact the IPHC office (206) 634-1838). If there is no Port Sampler available, National Marine Fisheries Service enforcement officers in the U.S. or Archipelago Marine Research port validators in Canada should be notified. The third option is to try to collect the data by yourself.

A list of halibut tag types can be found on our Tag Page.


Where have all the big fish gone

For a simple question, this has a bit of a complicated answer. The simple answer is, they are still here. Or at least the same age fish are still here. For the past 15 years or so, halibut growth rates have been depressed to levels that haven't been seen since the 1920's. Both females and male halibut have the potential to grow rapidly until about age 10, about 2 inches per year for males and 2.5 inches for females. Thereafter, females have the potential to grow even faster, while males generally would slow down relative to female growth. Growth rates for these larger fish in the last 10 or so years are more on the order of one inch or less per year. This translates into a much smaller fish at any given age. There was a dramatic increase in halibut growth rates in the middle of this century, especially in Alaska. Sometime around 1980, growth rates started to drop, and now Alaska halibut of a given age and sex are about the same size as they were in the 1920's. For example, in the northern Gulf of Alaska, an 11-year-old female halibut weighed about 20 pounds in the 1920's, nearly 50 pounds in the 1970's, and now again about 20 pounds. The reasons for both the increase and the decrease are not yet known but may be tied to increased abundance of other species, such as arrowtooth flounder, and availability of food supply.1,2

1 Decadal changes in growth and recruitment of Pacific halibut (Hippoglossus stenolepis), William G Clark, Steven R Hare, Ana M Parma, Patrick J Sullivan, Robert J Trumble. Canadian Journal of Fisheries and Aquatic Sciences. Ottawa: Feb 1999. Vol. 56, Iss. 2; pg. 242, 11 pgs
2 RARA 2009: Populations Assessment Document


Wouldn't a maximum size limit help preserve the female spawners?

No. IPHC biologists see no benefit to preserving the largest females from a conservation standpoint. There are plenty of small halibut available to grow into the large fish we all like to catch and eat. According to the Bluebook handout for the 1999 IPHC Annual Meeting, implementing a maximum commercial size limit of 50 inches (or 150 cm, about 80 lbs) does not appear to add substantial protection to the stock to justify a change in regulations.5 While large females can each spawn many more eggs than medium-sized females, their overall reproductive contribution is nevertheless small as not many females reach those large sizes under the current reduced growth rates.6

5 1999 IPHC Bluebook . Page 42
6 1999 IPHC Bluebook . Page 49


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