Spike in salmon shark sightings near Kodiak stumps researchers

A salmon shark caught arsenic bycatch connected a commercialized sportfishing vessel and tagged for research. (From NOAA Fisheries)

Salmon sharks look to beryllium turning up successful Kodiak fishermen’s nets and washing up connected nationalist beaches astir Kodiak Island successful greater wave this summer. But location isn’t capable information to find if nan shark organization is increasing disconnected nan seashore of Alaska.

On Sunday, a Kodiak resident stumbled upon a salmon shark washed up connected Boy Scout Beach, adjacent nan Buskin River. And a fewer fishermen astir Kodiak person reported seeing aliases catching much sharks than accustomed successful their sportfishing cogwheel this summertime too.

A type of shark, astir apt a salmon shark, caught accidentally successful a fishermen’s nett astir Kodiak Island. (Mike Wall/KMXT)

The type is simply a relative to nan overmuch larger awesome achromatic shark. It looks menacing, but Oregon State University interrogator Alexandra McInturf says it is harmless to humans.

“Historically they were called salmon sharks because they were seen astatine nan stream mouths up successful Alaska eating salmon,” McInturf said.

McInturf researches salmon sharks, among others species, astatine what Oregon State calls its Big Fish Lab. Even though Kodiak Island has seen dwindling runs of pinkish salmon and Chinook this summer, McInturf said salmon sharks are known to eat a assortment of forage fish, chiefly ones that are commercially viable for illustration pollock, herring and moreover squid. Salmon sharks’ eating habits besides dangle connected respective different factors for illustration their property and gender.

“They do not look to beryllium salmon specialists,” McInturf stated. “And truthful if location are mediocre salmon runs, past they mightiness person to displacement their foraging patterns to utilization different resources and that could beryllium why they are being encountered by different (fishermen) than previously.”

Research over nan past decade, from 2016-2021, suggests these predators play a domiciled successful nan dwindling Chinook salmon numbers. But nan nonstop nexus betwixt king salmon declines and salmon shark predation is unclear.

Similarly, it’s difficult to find nan full number of salmon sharks successful Alaska waters and nan differences betwixt stocks migrating from spot to spot up and down nan West Coast, on nan California existent to places for illustration Baja, and into nan Gulf of Alaska and Bering Sea. More information is being gathered connected nan animals’ residence scope arsenic nan Alaska Department of Fish & Game is tracking nan movements of salmon sharks for illustration Ada, an 8-foot female, tagged successful nan Northern Bering Sea a mates years ago.

McInturf besides points retired that moreover if much sightings of salmon sharks are being reported astir Kodiak Island this summer, nan sharks could person already been successful nan area successful greater numbers.

“They don’t inhabit two-dimensional space, right? Like they could beryllium astir but astatine depth. So successful summation to reasoning astir their distribution geographically, we besides person to deliberation astir their distribution passim nan h2o column,” McInturf explained. “So moreover if we haven’t been seeing them astatine nan surface, they could person been astir but possibly feeding connected thing much astatine depth.”

Salmon sharks person been seen arsenic acold northbound arsenic nan Bering Strait, astir nan Nome area, successful caller years and could proceed to migrate further arsenic ambiance alteration pushes their prey into colder waters. They are 1 of respective shark type that tin modulate their ain assemblage temperatures and are classified arsenic warm-blooded, according to McInturf.

Fisheries biologist Cindy Tribuzio, pinch nan Alaska Fisheries Science Center which is portion of nan National Marine Fisheries Service, agrees pinch McInturf; location is not capable drawback information to support nan thought that nan magnitude of salmon sharks being caught successful fishermen’s nets, arsenic bycatch, is expanding successful nan Bering Sea and Gulf of Alaska.

“What’s being observed (in Kodiak) could correspond organization changes. It could besides conscionable correspond nan stocks being condensed successful a definite area because of a definite nutrient source. There are truthful galore different things that could beryllium starring into this study that is going connected correct now,” Tribuzio said.

Tribuzio useful astatine nan Auke Bay Lab successful Juneau and handles nan banal assessments for sharks successful nan Bering Sea. She said it’s difficult to estimate nan number of salmon sharks, and different shark type wide successful Alaska, partially owed to a deficiency of information coming from nan state’s commercialized fisheries.

Since salmon sharks are not targeted for a circumstantial commercialized fishery, nan latest investigation suggests location is no overfishing occurring successful nan Bering Sea aliases Gulf of Alaska (Aleutian Islands region).

The past banal appraisal of salmon sharks in Alaska, and others for illustration Pacific spiny dogfish, Pacific sleeper shark, was released successful 2022 and nan adjacent 1 won’t beryllium completed until 2026. In nan meantime, a caller forage study astir salmon sharks’ fare from McInturf’s squad astatine Oregon State University is expected to beryllium released later this year.