Fishermen's News - The Advocate for the Commercial Fisherman

One Fish, Two Fish, the New Blue Rockfish

Researchers say the familiar fish is actually two separate species

 

(TOP) The Blue rockfish harvested off the California coast has been found by researchers to actually be two significant species. (ABOVE) The new species, named the Deacon rockfish, can be identified by the white bands around its head that resemble a clerical collar.

A commercially significant species of rockfish, it seems, has a dual personality.

Researchers from Oregon State University (OSU), the Oregon Department of Fish and Wildlife (ODFW), and the California State University-Los Angeles performing a new analysis of the Blue rockfish harvested off the Oregon and California coasts have confirmed that the Blue is actually two separate and distinct species. The analysis proves their separate status through distinguishing differences in anatomy, color, geographic distribution, behavior and genetics.

Ben Frable, an OSU graduate student, said prior studies revealed some genetic differences between these two groups, noting that "various researchers have written about the Blue rockfish for years, but it has never been morphologically described as two separate species." The research team named the new species Deacon rockfish as a tribute to the nickname Portuguese fishermen around San Francisco gave Blue rockfish during the 19th century. They called it the "priest fish," because the white bands around its head resembled a clerical collar.

ODFW marine biologists say the discovery could alter rockfish harvest regulations, but certainly not soon enough to lift restrictions fishermen are operating under this season. Fishery managers say Blue rockfish count as a single species under the "minor near-shore rockfish complex" of 11 species, which has "significant reductions" in allowable harvest. Three members of the complex – China, Quillback and Copper rockfish – are off-limits for recreational fishermen this year, which shifts angling efforts to Black and Blue rockfish.

"Black rockfish are the major target of the complex and have a separate quota, set at 440 metric tons," said D. Wolfe Wagman, an ODFW marine biologist. "The Blue rockfish quota is much lower, and ODFW is concerned that if fishing efforts exceed that quota, all groundfish fishing would have to stop in Oregon, because even incidental catch and release of Blue rockfish would exceed the quota."

Discovery of the Blue's dual-species identity could alter the equation. While both species are found off the Oregon coast, the original Blues are more prevalent in California waters, the new Deacons range mostly from northern California to the Salish Sea near Vancouver, British Columbia, Canada. Researchers have not yet found evidence of hybridization.

"This may eventually lead to separate quotas," Wagman noted. "But as long as they are still categorized in the minor near-shore rockfish complex, they have to be managed as one group with other rockfishes in the complex."

Researchers say they have no reason to consider either the Blue or Deacon rockfish endangered, but Brian Sidlauskas, OSU ichthyologist and curator of fishes, said population surveys are needed. "The original Blue rockfish is considered exploited in parts of California, but the Deacon rockfish seems fairly robust from Oregon northward," he noted.

In 2012, Wagman asked Sidlauskas to formally study the taxonomy of the Blues. Andres Aguilar, a fish scientist from California State University-Los Angeles, who had participated in some of the earlier genetic analyses, joined the team, as did Frable, who examined the historical record dating to the 1800s, including preserved specimens in ichthyological collections throughout the United States and Canada.

Frable examined 130 Blue rockfish museum specimens collected during the past century from Vancouver Island to northern Baja, Mexico, looking for differences and similarities. Frable and his colleagues focused on 35 different measurements – among them spines, scales, eye width, dorsal fin length, tip-to-tail length, and other characteristics – to determine differences in body shape, proportion and growth. Some measurements were clearly distinct between the species.

"There are also some possible differences that may require more research," Frable said. "In talking with port samplers, it seems like Deacon rockfish are caught in slightly deeper waters, while the original Blue rockfish is more often found closer to shore. That could prove to be helpful from a management standpoint."

Sidlauskas said the research underscores the importance of preserving historical collections of fishes and other species, because such collections "provide a wealth of data over time and space. That historical perspective is invaluable in providing context for what we see today."

This time, the painstaking research gave commercial fishermen a new species to target once fishery managers decide how to handle the situation, including those important quotas.

 
 

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