Rockfish (Sebastes spp.)

Resources

Status

  • BC: Various
  • COSEWIC: Various
  • SARA: Various
  • Global: Various

Description

Rockfish (Sebastes spp.), are a fascinating genus of fish with many unique characteristics that make them quite distinct from others. Their Latin name Sebastes translates to “magnificent” in Greek. British Columbia’s surrounding ocean houses nearly 40 species of Rockfish, with a total of around 96 species in the North Pacific, and approximately 102 species worldwide.

Rockfish species have exceptionally long lifespans, ranging from approximately 50-120 years old. Rockfish can be aged by their middle inner ear bone, called the otolith bone. The oldest rockfish recorded was found off of the Alaskan coast and was 205 years old!  From a human point of view, this means more than four generations of your family could visit Galiano Island and the same rockfish could be found living off shore of your island home.

Due to their longevity, rockfish do not reach sexual maturity until much later in their lives; 50% of them will not mature until the ages of 12-18. Because of this, it takes several years for their population to grow. Eggs produced by older rockfish are much higher in volume – compared to younger rockfish – while also having a higher rate of survival.

Habitat

Rockfish find comfort on rocky surfaces such as the ocean floor. They are non-migratory species and have a small range of habitat resulting in them occupying a small area for their entire lives.

Range

Rockfish are found in the temperate north and south Pacific and Atlantic Oceans.

Threats

Rockfish populations are declining due to a number of external threats. Several rockfish species are now listed as threatened or “of special concern” by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Throughout British Columbia, the management of rockfish is split up into outer shore and inner shore areas due to the fact that rockfish located inshore are experiencing more severe declines. Protection of rockfish through Rockfish Conservation Areas (RCA’s) that restrict fishing activities, and community-based education, are essential to combat the human impacts that threaten rockfish in today’s world. Some of the prominent threats that rockfish face are:

Barotrauma: Inshore rockfish can live in depths up to 300 meters, which makes them vulnerable to barotrauma when exposed to catch and release fishing. Barotrauma is caused when the swim bladder of a fish expands due to rapidly changing pressure. Relating this to a human perspective, divers can experience decompression sickness, which is caused by rapid changing pressure when coming up to the surface too fast, just like rockfish! Thus, when rockfish are brought to the surface too quickly, their swim bladder expands, resulting in them becoming buoyant and not being able to swim back down to the bottom of the ocean. Therefore, even if rockfish are released after capture, they are often stuck on the surface, remaining vulnerable to predators. As their swim bladders expand, this can also cause rockfish’s eyes to bulge and their stomachs to come out of their mouth. It is because of these events that make rockfish more vulnerable to catch and release fishing compared to other fish.

Overfishing: Fisheries typically target larger sized fish. However, these larger fish are usually the oldest fish, and therefore the fish that produce more eggs of a higher quality. Thus, when large rockfish are targeted, rockfish populations become hindered in their capacity to grow. Additionally, due to their small range, they are easy targets for bycatch of fishers (targeting one species but unintentionally catching others in the process).

Lack of Awareness: Throughout British Columbia, including the Southern Gulf Islands, 164 Rockfish Conservation Areas (RCA’s) have been implemented. The establishment of RCA’s is to restrict certain activities that are harmful to rockfish. However, they do have their obstacles to overcome as the public knowledge of these RCA’s appears to be lacking, and people are often not familiar with what activities are permitted and what is not within RCA’s. Additionally, fisherman may have challenges in discerning the location of RCA boundaries. It is because of these factors that prohibited activities still occur within RCA boundaries, thus rockfish species remain threatened. Knowledge plays a large factor in the success of RCA’s and without adequate public awareness, successful conservation can be challenging.

Galiano Status

At least 7 species of rockfish have been documented in the waters around Galiano Island, including several COSEWIC-listed species.

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