The 1960s and 1970s was a time of plenty in Kodiak, the heyday of the king crab fishery, and Kodiak had a boomtown bustle.

Crab stocks underwent a precipitous decline in the late 1970s, and the commercial fishery was closed in 1983. Since then, neither Kodiak nor the king crab have fully recovered.

William Bechtol, a doctoral candidate in fisheries at the University of Alaska Fairbanks School of Fisheries and Ocean Studies, has been conducting research to try to answer the mystery of why the king crab population crashed and why it has failed to recover, even with no Kodiak commercial fishery for 26 years.

Commercial fishing for Kodiak king crab dates back to the 1930s. It remained a minor fishery until the 1960s, when it underwent rapid growth. By the late 1960s, the fishery was shifting from small boats lacking refrigerated seawater (RSW) to a fleet of larger RSW-equipped boats. This transition resulted in the fishery expanding into offshore waters.

The king crab harvest hit a peak of 94.4 million pounds in 1965, but declined sharply in subsequent years. Catches fluctuated at lower levels throughout the 1970s until the stock collapsed in the early 1980s.

Bechtol theorizes that in years prior to the expansion of the fishing fleet, male crab recruitment outpaced the commercial catch. But by the mid-1960s, the commercial harvest was eliminating older males from the population.

Throughout the 1970s the fishery was more dependent on recruitment-class males. Thus, the fishery fluctuated, with catches going up in good recruitment years.

The population sex ratio eventually became skewed toward females, which led to reproductive failures and to population collapse.

Closure of commercial king crab fishing in Kodiak waters for the past 25 years has failed to induce any substantial recovery to crab stocks.

Alaska Department of Fish and Game (ADF&G) crab surveys indicate king crab are concentrated in inshore waters. This is especially true for young crab in their first two years of life.

ADF&G pot survey data show that Pacific cod have likewise shown increasing concentrations in inshore waters.

Crab recruitment is derived most notably from survival in younger life-stages. Juvenile crab molt several times per year and are especially vulnerable to predation.

Bechtol theorized that cod predation on juvenile crab is the biggest factor preventing recovery of the crab stocks.

Although Bechtol avoided the issue of global warming and how it has impacted the chain of events, he did note that the king crap collapse coincides with a climate regime shift that commenced in the late 1970s.

The same unfavorable environmental conditions have persisted and continue to impede king crab recovery. Thus, Kodiak can anticipate continued closure of the king crab fishery for the foreseeable future.

Mirror writer Harry Dodge can be reached at hdodge@kodiakdailymirror.com.