Can Pacific Salmon Adapt to Climate Change?

by Emil Morhardt

Chinook (king) salmon deposit their eggs in the cobbles of Pacific Coast streambeds, where they, and the subsequent developing juveniles spend months before heading out to sea. Some of these streams can get quite warm by salmon standards, and more than one major run has been heavily depleted by temperatures higher than 24 °C which seems to be generally lethal to this species. As global warming progresses we can expect more salmon streams to reach this temperature, so an important question is whether these fish have either the developmental plasticity or the genetic variability that will allow them to adapt. Muñoz et al. (2015) crossbred 16 wild chinook salmon caught at Canada’s Quinsam River Hatchery so as to get 64 different genotypes, then reared half of them at the hatchery ambient water temperatures and the other half at temperatures 4 °C higher. They then looked to see if cardiac function, the apparent limiting factor in high temperature mortality, was shifted to higher temperatures. Continue reading

Plastic Ingestion in Mediterranean Sperm Whale

by Chloe Mayne

Marine debris has become an extensive problem in the oceans today. Plastics and other debris affect over 250 species of marine organisms by entanglement and ingestion. Current studies have shown large marine mammals to be affected by entanglement, but few studies exist on the affects of ingestion of plastic debris. There have been three recorded standings of sperm whales with large amounts of plastic and marine debris in their stomachs. In the Mediterranean Sea, the population of sperm whales is considered to be a separate species and has had a decline in population over the past 20 years. This decline has been attributed mostly to boat strikes and entanglement, with no knowledge of the affects of plastic ingestion. Stephanis et al. (2013) examined a stranded sperm whale in the Mediterranean Sea that had ingested a large amount of marine debris. They discuss the results in terms of the spatial distribution of sperm whales and the anthropogenic activities in the area. In the Mediterranean Sea, the species is found near Almería and the Strait of Gibraltar. This study found that the whales feed in an area with lots of debris from the greenhouse industry. In the sperm whale examined, the cause of death was determined to be gastric rupture from the build up of debris. Continue reading

Under-reported Overfishing by Chinese Threatens World Fisheries Estimates

by Hannah Tannenbaum

Fisheries catch data are the only real means for the fisheries industry, economists, and environmentalists to ascertain the population status of fished stocks. Therefore, accurate reporting of catch data is of the utmost importance. It was discovered in 2001 that China was drastically over reporting their domestic catch in order to achieve the appearance of uninterrupted expansion and success. China has an immense fishing fleet, but is also outside of agreements regarding EEZ and FAO of the UN, and therefore their catch records are important for global estimates, but particularly unreliable as currently reported. While estimates have been made to correct for decades of over-reporting in Chinese domestic fisheries, they are also major participants in distant-water fisheries. Pauly et al. (2013) used statistical extrapolations to estimate the Chinese distant-water catches and found severe under-reporting compared to the figures reported to FAO. While the interpolations have high levels of uncertainty, they nonetheless suggest immense inaccuracy of global fisheries catch statistics which has wide implications for employment, economics and ecology. Continue reading

Plastic Pollution and Associated Microorganisms in the North Pacific Gyre

by Chloe Mayne

Anthropogenic plastic pollution in the ocean has become extremely harmful to marine organisms and their environment. These problems include ingestion, entanglement, leaching of chemicals and adsorption of organic pollutants. The most common marine debris are small plastic fragments, which often are larger items that have been degraded. Microorganisms likely interfere with the degradation process as a result of biofilm formation on plastic surfaces. They may block plastic from UV radiation and photo-catalysis, which would increase plastic longevity. Inversely, microorganisms may accelerate degradation. Fouling microorganisms are extremely important to understanding the problems with plastic pollution, yet they have not been adequately studied. In this experiment, Carson et al. (2013) examine the abundance and diversity of microorganisms on plastics in the North Pacific Gyre. Continue reading

The Effect of Climate Change on Prawn Fishing in Bangladesh

by Shelby Long

Nearly 400,000 Bangladeshi people are financially dependent on the fresh water prawn market. Bangladesh offers the natural resources and ideal climate to support prawn farming from wild postlarvae. In 2002, a ban was placed on the fishing of wild postlarvae by the Department of Fisheries in Bangladesh. However, this ban is not strongly enforced, so many locals who rely on the market to make a living continue to fish. Ahmed et al. (2013) examines the effect of climate change on prawn fishing in the Pasur River through variables, including cyclones, salinity, sea level rise, water temperature, flood, rainfall, and drought. The Pasur River ecosystem, more specifically the prawn postlarvae, is highly vulnerable to climate changes because it is only one meter above sea level. Researchers surveyed and interviewed local fishermen, government fisheries officers, policymakers, and non-governmental organization workers. They also conducted focus group discussions with fishers and local community members regarding the various climate-affected variables under study. Ahmed et al. determined that prawn postlarvae catch has gradually decreased by approximately 15% over the past five years, with cyclones being the most significant climatic variable affecting the catch. Decreases in postlarvae prawn catch impact the health and socioeconomic well-being of local fishermen, many of which are women and children. Continue reading

Behavior Alterations in Temperate Fish with Elevated-CO2

by Jennifer Fields

Anthropogenic CO2 emissions are causing an increase in dissolution of CO2 into the oceans resulting in ocean acidification. Teleost fish have been thought to have a high tolerance to ocean acidification because their specialized gills allow them to regulate the pH of their blood. However, recent studies have reported strong behavioral effects of ocean acidification in tropical coral reef species. The studies found that there was a diminishment of risk-assessment, learning, lateralization, and prey detection with increased dissolved CO2. But, little is known about the behavioral changes of temperate fish under the same conditions. Jutfelt et al. (2013) observed behavioral disturbances in boldness, exploratory behavior, lateralization, and learning in temperate fish under end of century ocean acidification conditions. The findings suggest that behavioral changes from increased CO2 are not limited to sensitive tropical species and could affect fish on a global scale by the end of the century. Continue reading

Resilience of Marine Turtle Regional Management Units to Climate Change

by Samantha Thompson

Scientists are searching for ways to avoid losing biodiversity to global warming. One way is by enhancing species resilience to environmental change. Resilience is the ability of an ecosystem or species to maintain key functions and processes in the face of stresses or pressures, either by resisting and/or adapting to change. Fuentes explored the resilience of 58 marine regional turtle management units (RMUs) to climate change, including all species of marine turtles worldwide. Using expert opinions from 33 different IUCN-SSC Marine Turtle Specialist Group respondents, the researchers were able to develop a Resilience Index. This was used in order to consider qualitative characteristics of RMUs such as population size, rookery vulnerability, and genetic diversity, and non climate related threats, such as fisheries, take, and coastal development. Through this information researchers were able to identify the world’s 13 least resilient marine turtle RMUs to climate change. Continue reading

Do Marine Protected Areas Save Seychelles Sea Cucumbers?

by Neha Vaingankar

Marine protected areas are a major cause of dispute especially in coastal and island regions like Seychelles, off the western coast of Africa. In recent times, tropical regions all over the world have experienced a huge boom in fishing of holothurians (sea cucumbers). Almost all of the holothurian fisheries are considered fully exploited, in decline, or entirely collapsed. The reason for the high demand is for the holothurian’s medicinal purposes as well as its supposed aphrodisiac qualities. In many tropical coral reef regions, locals rely on these invertebrates for their livelihoods. However, due to the density-dependent reproduction patterns and late maturing of these organisms, holothurians are very vulnerable to over-exploitation. Many MPAs were established in Seychelles 20 years ago that pre-date the wave of heavy exploitation in current times. Cariglia et al. (2013) aims to understand the effectiveness of these MPAs and measure the economic value of these holothurians. Continue reading

From Primary Predator to Picked-on Prey: Shark Fishery in the Pacific Ocean

by Hannah Tannenbaum

In 2001 sharks were first listed as endangered species, and since then several measures have been enacted towards their protection. However, the majority of shark fishing is an incidental byproduct of purse seine and long-line fisheries which operate outside of national Exclusive Economic Zones (EEZ). Therefore the effectiveness of international treaties banning shark finning is hard to discern. Another major difficulty in assessing the effectiveness of conservation is the paucity of data on shark population size and structure. Clarke et al. (2013) collected and analyzed onboard observer data on shark catches from 1995–2010 in order to evaluate the threat to sharks from commercial fishing, and determine changes in shark populations after finning bans were established. The authors analyzed data on blue, oceanic whitetip, silky, and mako sharks because of their tendency to appear as bycatch in the Pacific tuna fishing industry. Through the analysis of observer data, no clear trend of reduced catches was found consistently for any species, any area, for either type of fishery. The authors suggest that shark retention bans may have a greater impact on population size than finning bans, and that management and monitoring must be made more consistent in order to properly evaluate conservation. Continue reading

Plastic Debris in Predatory Pelagic Fishes of the North Pacific

by Chloe Mayne

The North Pacific subtropical gyre contains large patches of marine debris and plastic. Recently, there have been reports of marine debris ingestion by sea birds, marine mammals, and fishes. Plastic debris is harmful to marine life, resulting in entanglement and decreased mobility, decreased nutrition or suffocation. Plastic also allows harmful organic contaminants to enter the marine environment, but there have been few experiments conducted on plastic ingestion in large marine fishes. Choy and Drazen (2013) studied 7 species of large pelagic fish for evidence of anthropogenic debris ingestion. Nineteen percent of the specimen had marine debris, primarily plastic or fishing line. A large majority of these species are thought to be mesopelagic fish that don’t come close to surface waters where marine debris is usually found. Plastic in pelagic fish shows the possibility of plastic pollution making it’s way through the food webs. These results are key in understanding the widespread nature of debris and plastic pollution in the ocean. Continue reading