Author Archives: katherine lam

The Greater Impacts of Fisheries and Environmental Change than Seal Predation in the Baltic Sea

With the declining fish population, many commercial fisheries and artisanal fishers are worried. They see the recovering seal population as competitors for the dwindling fish stocks and this economic toll has led some fishers to take out their anger and frustration for on the seals, which truthfully is wrong! Researchers are working hard to scientifically prove that seals are not responsible for the decline in fish biomass in the Baltic Sea but rather the anthropogenic and environmental factors that are prevalent in the region.

“Freshly Caught Cod Fish” by Emad Basiri at Granville Island Vancouver BC, 2019

Dr. David Costalago by Emad Basiri at the Aquatic Ecosystems Research Laboratory, 2019

Dr. David Costalago, a postdoctoral fellow from University of British Columbia’s Institute for the Oceans and Fisheries is helping shed some light on this controversial topic. Research done by Dr. Costalago and his team has helped to serve as a guide for a more comprehensive approach to management and conservation of seals. His research concludes that the recovering seal population is not to blame for the plummeting number of fish, instead, environmental changes, and overfishing cause more significant decreases in the fish population.

 

Source: SCIE 300 SO Project 213-6 Song “Kiss from a Rose” by Seal

By modelling future environmental scenarios, the researchers investigated how grey seal predation affected the fish stocks in the Baltic Sea. The data modeling software, Ecosim with Ecopath,  allowed researchers to study and model the feeding interactions between different marine mammals from 1974 – 2012. In addition, the models allowed the researchers to look into the consumption rates of fish by grey seals and compare that to the amount of fish caught by Baltic fishermen. 

Source: SCIE 300 SO Project 213-6 Song “Kiss from a Rose” by Seal

Dr. Costalago’s research brings awareness to the seal population in the Baltic Sea, but further research is needed to accurately determine the economic impact the seals are having in the Baltic. For instance, more data over a longer time period needs to be collected, especially along coastal regions because it’s where most Artisanal fishers are. 

“I know for a fact that some of the fishers are struggling nowadays and I know that seals might be playing a role in their struggles so that needs to be addressed,” said Dr. Costalgo. After talking to a local BC fisherman, he mentioned that the damages the seals would cause would lead to several hours of untangling lines and additional money spent to replace damaged equipment.

“We know that the seal population are not affecting the fish biomass but the economic problems that some fishers have to face also need to be addressed by the government” – Dr. David Costalago

 

Dr. Costalago’s study is helping other ecologists and government officials to find ways to manage the seals and fix their own relationships with the fishermen with regards to fishing policy. This has brought attention to the unjust treatment of seals and the significant impact that the environment and fisheries have on the fish biomass.

By Group 213-6: Emad Basiri, Tenanye Haglund, Katherine Lam, Arrthy Thayaparan

The Fall of Sea Stars

1986-014-01: Sunflower seastar

1986-014-01: Sunflower seastar” by August Rode is licensed under CC BY-SA 2.0

Once an abundant species of sea star, the sunflower sea stars have become harder to find on the West Coast of North America. A recent study co-led by the University of California, Davis, and Cornell University claims that the combination of ocean-warming and an infectious wasting disease has led to the declined population of these large sea stars.

The sunflower sea star is one of the largest sea star species, they can grow as big as manhole covers. Commonly found in the northwest Pacific, they were once regularly found from Southern California to Alaska and some of the largest sunflower sea stars could be found in Puget Sound, British Columbia and Alaska.

In 2013 and 2014, a disease called sea star wasting syndrome affected around 40 different species of sea stars, including the sunflower sea star, to die off along the North American Pacific coast. Symptoms of the disease would be lesions and tissue decay, which the body structure of the sea star would start to breakdown. For example, their arms may twist and fall off and the sea stars would become limp. Eventually, the sea star would disintegrate and melt away into a white, mushy blob and no longer be a sea star. It is unclear where this disease originated from but researchers believe ocean-warming might be the reason why this disease continues to affect the sea stars and why the sea star population is not recovering fast enough.

Dying sea star

Dying sea star” by Oregon State University is licensed under CC BY-SA 2.0

Ocean-warming is an effect of global warming. The ocean absorbs excess heat from the atmosphere which contains greenhouse gas emissions, which leads to rising ocean temperatures. Increasing ocean temperature can affect many marine species and ecosystems. Warming of the oceans have been linked to the increase and spread of diseases of marine species.

The sunflower sea star species has been detrimentally affected by sea star wasting syndrome. The study conducted by Dr. Harvell and her colleagues collected data over eleven years to show how the population of sea stars have diminished due to this disease. In addition, scientists also found that the ocean water has warmed almost 4 oC within a four-year span in some areas. Results of the study showed the population crash of sunflower sea stars from Southern California to Alaska whilst tracking patterns of unusual warming in the Pacific Ocean. The sunflower sea star is shown to be highly susceptible to this wasting disease because they do not have a complex immune system. As a result, the data showed an 80 to 100% decline over the period of the study.

Sunflower Star Imperiled by Sea Star Wasting Epidemic” by Hakai Institute

If the sunflower sea star dies off, this should be an important indicator of the effects of ocean-warming and its impact on marine ecosystems. Sunflower sea stars are voracious predators in the deep and shallow waters of the northwest Pacific, and if these sea stars were to go away we could see an unbalanced ecosystem in our waters.

– Katherine Lam