| Butter clams (gáal’), cockles (yalooleit) and blue mussels (yaak) are some of the most commonly harvested shellfish in the Hoonah area and all are extremely vulnerable to the effects of climate change. Community members have shared a great deal of concern about the continued safety of shellfish in a warming climate. One tribal member said her elders used to harvest year-round, but by the time she was a child she was told to harvest only in months with an R. Now, she relies on testing from a lab in Sitka to know when to harvest since it can be dangerous any time of year. Another tribal member said she’d been noticing scarcity the past few years and had had a hard time finding enough cockles for her family. A third said that she had noticed some of her favorite clamming beds were no longer as productive as they had been and that she was having to search for new places to find shellfish due to the way the shoreline had been reshaped. |
Primary Risks
OCEAN ACIDIFICATION CAN DISSOLVE THEIR SHELLS, KILLING THEM OR SLOWING GROWTH.
Larval shellfish are particularly vulnerable because of the mineral they use to build their shells. In adult shellfish, several species were found to have 40 percent thinner shells and 17 percent slower growth when placed in more acidic water that represents what ocean conditions could look like in the next hundred years. With thinner shells, the shellfish are more vulnerable to being eaten by other animals, and the smaller size means harvesters need to exert more effort to get the same amount of meat. Since some species are more resilient in acidic conditions, the composition of shellfish beds may change, with scallops being more resistant than many other kinds of bivalves.
WARMER WATERS AND HIGHER AIR TEMPERATURES CAN COOK SHELLFISH IN THEIR SHELLS.
Following heatwaves in Washington, there were massive die-offs of shellfish along the western coast of the US and BC. Since shellfish tend to mostly stay in one spot, they have fewer opportunities to seek out cool spots to hide from the heat, which can result in them cooking in their shells. This is particularly problematic in inner coastal areas, like Port Fredrick. Cockles, which live in much shallower sediment, were also more at risk, as compared to species like butter clams that dig deeper where the sand remains cooler.
HARMFUL ALGAL BLOOMS ARE EXPECTED TO GET WORSE, WHICH CAN MAKE SHELLFISH TOXIC TO HUMANS AND OTHER ANIMALS THAT RELY ON THEM FOR FOOD.
The plankton Alexandrium can produce a variety of paralytic shellfish toxins, including the highly toxic saxitoxin which causes Paralytic Shellfish Poisoning. The plankton thrive in warm water conditions with higher levels of CO2 and in lower salinity, all of which are likely to occur as a result of climate change. While the traditional adage about only harvesting in months with an R in them has kept people safe for thousands of years, as conditions change and blooms become larger and more frequent, the number of months in which it is unsafe to harvest is likely to expand. Saxitoxins can also last inside of some species of shellfish for several years after a large bloom, further impacting shellfish safety.
OCEAN ACIDIFICATION CAN ALSO DAMAGE MUSSEL’S ABILITY TO HOLD ON TO ROCKS AND IMPACT THEIR BREEDING. Shellfish such as oysters and blue mussels that need to grip onto their surroundings may lose their ability to do so, because the proteins required to build that part of their body can be weakened in acidic conditions. Breeding success may also decline, as some studies on oysters found decreases in acidic environments while others found no effect, which would overall reduce the population of shellfish available.
WHERE SHELLFISH CAN BE FOUND WILL CHANGE DUE TO SEA LEVEL CHANGES.
Post-glacial rebound is predicted to outpace sea level rise at least through the end of the century and will reshape shoreline habitats where shellfish are found. The flat sandy and muddy regions that are the richest shellfish beds are most vulnerable to sea level changes. While the overall amount of habitat is not predicted to change, community members will need to find new clam beds, which may be further from town.
GIVEN THE LOW ENVIRONMENTAL IMPACT OF CULTIVATING SHELLFISH, NEW ECONOMIC POSSIBILITIES MAY BENEFIT THE REGION.
Unlike land animals like pigs and cows, shellfish don’t release large amounts of CO2 or methane into the atmosphere, making them a much eco-friendlier source of meat. They can also help clean the water and sequester carbon, and as more people turn towards green solutions in the fight against climate change, the popularity of shellfish is likely to rise. This could result in more jobs and economic opportunities for people interested in starting aquaculture projects in Southeast Alaska.
Adaptation strategies
SHORT-TERM GOALS
1.1: Continue water samples to monitor for Alexandrium blooms near key shellfish harvesting locations near town.
1.2: Continue monthly sampling of shellfish to test for biotoxins in collaboration with SEATOR partners.
1.3: Continue biomass survey in coordination with the SEATOR partners to monitor size and quantity of shellfish
MID-TERM GOALS
2.1: Educate community members about the risks of paralytic shellfish poisoning and maintain up to date reports on the level of biotoxins detected through the SEATOR network
2.2: Organize events and classes for community members to learn about sustainable shellfish harvesting and safe storage practices.
LONG-TERM GOALS
3.1: Consider possibilities for the construction of clam gardens or shell hash development near town.
3.1.1: Target research in areas of rock/sediment
3.2: Research options for enhancing and protecting eelgrass beds
3.3: Work to create plans for shellfish stock restoration and propagation.
3.4: Something about preventing competition from external users?
3.5: Research possibilities for enhancing abalone stocks near Hoonah