Sea Otter & Fisheries

The Potential Impact of Sea Otters on Fisheries

Facts and Frequently Asked Questions

A simple question, “Will sea otters affect fisheries when they return to Oregon?” is often asked because of concern that a return of sea otters will result in harm to commercial and recreational fisheries, which are economically and culturally important to the Oregon coast.

The answer is complex and gives hope. Oregon’s ocean fisheries are highly diverse, pursued for a variety of species in a range of locations with different gear depending on the time of the year. The location and number of sea otters in relation to each of these fisheries, as well as their behavior, are variables that will determine whether sea otters might affect a particular fishery in a particular location

The relationships between species and their ecosystems are not always direct. Many fisheries are likely to be helped by the return of sea otters because, as a keystone species, sea otters are essential to promoting and maintaining the diversity, productivity and resilience of marine and estuarine ecosystems that support all fisheries. While sea otters may reduce the abundance of shellfish in some localized areas, they will also enhance the abundance of finfish through their beneficial effects on kelp and seagrass.

Reintroducing sea otters to a new home on the Oregon coast will be complex and expensive. That means that the number of animals actually released in Oregon may be no more than one hundred, scattered in a few locations at most, and not in thousands or along the entire coast as some envision. Even if these reintroductions are successful, it will take several decades for the population of sea otters to reach many coastal areas and, potentially, their fisheries.

To be clear, the Elakha Alliance understands the economic and cultural importance of commercial and recreational fisheries to the Oregon coast. We are confident that returning sea otters to Oregon will benefit and sustain Oregon’s fisheries. But where the possibility of harm exists to a fishery, we are committed to working with fishermen to avoid, reduce or mitigate such effects.

Sea otters do not hunt or eat finfish in the lower 48 except in rare instances. Instead, they target calorie-rich shellfish to efficiently meet their high energy demands. They dive only as deep as necessary to find food, typically 90 feet or less and relatively close to shore, although they can dive much greater depths.

Sea otters stay put. Once sea otters are established in an area, they tend to stay put. Mother sea otters have one pup per year, not a litter, and stay in a small home area to save energy while nursing and feeding the pup. Unlike seals, sea lions and whales, neither male nor female sea otters migrate. Thus, the area occupied by sea otters will expand slowly as the population increases. Analysis shows that Oregon’s sea otter population will likely be small and confined to localized habitat areas for many decades.

Oregon is not Alaska. The enormous population of sea otters in Southeast Alaska and its impacts on local shellfisheries are the result of the nearly perfect conditions for sea otters there. A complex geography of islands, coves, rocks and inlets offers suitable habitat in almost every direction for a sea otter seeking new food resources, allowing for extremely rapid population growth. By contrast, the Oregon coast is more or less linear north to south, offering disconnected areas of suitable habitat along exposed coastal sections. The relatively rapid drop-off of the continental shelf means there is only a narrow strip of habitat along the coastline where depths are suitable for sea otters. Because of this habitat disparity, Oregon’s sea otter population will remain small compared to the population in Southeast Alaska.

It will take time for Oregon’s population to grow. An initial release of sea otters will likely involve no more than one hundred animals released at a few selected locations. A computer model based on scientific studies predicts an establishment period in which the number of animals will decline to a fraction before slowly increasing and, after twenty-five to thirty years, returning to the number initially released. 

Frequently Asked Questions:

No, because sea otters do not hunt finfish such as groundfish, salmon, ling cod, halibut, tuna, and nearshore rockfish that are targets of commercial fisheries. In addition, many of these fisheries take place in waters deeper than where sea otters hunt for food. And fisheries for invertebrates such as market squid, pink shrimp and spot prawns will not be affected because sea otters do not regularly prey on these species. 

Sea otters prefer relatively shallow water close to shore whereas most commercial crabbing is pursued in deeper waters. Thus, sea otters are not likely to affect Oregon’s commercial Dungeness crab fishery in crabbing areas across the continental shelf. However, sea otters may compete for some adult crabs in shallower “beach” crabbing areas. Studies in California show that, in general, sea otters have had no impact on commercial Dungeness crab harvest. 

The only commercial shellfish dive fishery in Oregon is for red sea urchins at sites on the southern coast. If sea otters are released in that region, that fishery will almost certainly be impacted. At present, red urchins and their fishery are greatly limited by the spread of purple urchin barrens and the loss of kelp forests, which sea otters will help to combat. A commercial dive fishery for clams is conducted in Tillamook Bay which will likely be more than hundred miles from any release of sea otters and would thus not be affected.

No. Sea otters will not harm recreational fisheries for salmon, rockfish, ling cod and other species for the reasons stated in Answer 1. Instead, they will benefit recreational fisheries by helping to restore and protect the kelp forests and eelgrass beds that provide crucial habitat in the life cycle of nearly all of these fish species. In addition, the presence of sea otters in a region is highly likely to draw visitors to that area, enlarging the client base for charter boat recreational fisheries.

Recreational crabbing and clamming are pursued in some but not all of Oregon’s coastal estuaries. If sea otters enter an estuary where recreational crabbing or clamming occur, they may compete for crabs or clams and thus affect those fisheries. However, sea otters will also prey on invasive European green crab and other invertebrates and will benefit the estuarine environment by promoting the growth of eelgrass, which is crucial habitat for juvenile Dungeness crab.

No. Unlike sea lions, sea otters are unlikely to frequent local ports or other areas of high human activity. They are not likely to haul out on docks or piers and thus interfere with port operations or be in large numbers to prevent permit approvals.

There is little research about whether sea otters prey on commercially grown oysters and, if so, under what conditions. More research is needed. In Oregon, commercial oyster cultivation occurs in Coos Bay, Tillamook Bay, Yaquina Bay, Netarts Bay, and in a protected site at the mouth of the Umpqua River. Many of these operations grow oysters directly on mud substrate at locations some distance from the mouth of the estuary. It is possible that, over time, sea otters could find and prey on these oyster beds. If so, alternative cultivation techniques utilizing protective nets or cages may need to be employed.

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See relevant chapters in the Elakha Alliance Feasibility Study: