Saving Seafood

Does DNA in the Water Tell Us How Many Fish There Are?

July 8, 2020 — River water, lake water, and seawater contain DNA belonging to organisms such as animals and plants. Ecologists have begun to actively analyze such DNA molecules, called environmental DNA, to assess the distribution of macro-organisms. Challenges yet remain, however, in quantitative applications of environmental DNA.

In a research article published online in Molecular Ecology, researchers from the National Institute for Environmental Studies, Tohoku University, Shimane University, Kyoto University, Hokkaido University, and Kobe University, have reported a new method for estimating population abundance of fish species (or more generally, a target aquatic species), by means of measuring concentration of environmental DNA in the water. Their results suggest the potential of the proposed approach for quantitative, non-invasive monitoring of aquatic ecosystems.

DNA molecules are released from organisms present, are transported by the flow of water, and are eventually degraded. In a natural environment, these processes can operate in a complex way.

“This complicates and limits the traditional approach of population quantification based on environmental DNA where the presence of a definite relationship between the concentration of environmental DNA and population abundance has been critical, “explained Keiichi Fukaya, research associate at the National Institute for Environmental Studies and the lead author of the paper.

Read the full story at Environment Coastal & Offshore

Researchers examine nations losing fish species due to climate change

February 25, 2020 — As ocean warming causes fish stocks to migrate toward cooler waters to maintain their preferred thermal environment, many of the nations that rely on commercial fish species as an integral part of their economy could suffer.

A new study published in Nature Sustainability from the University of Delaware, the University of California, Santa Barbara and Hokkaido University, shows that nations in the tropics—especially Northwest African nations—are especially vulnerable to this potential species loss due to . Not only are  at risk for the loss of  stocks, the study found there are not currently any adequate policy interventions to help mitigate affected countries’ potential losses.

Kimberly Oremus, assistant professor in the School of Marine Science and Policy in UD’s College of Earth, Ocean and Environment, explained that when the researchers looked at , including the United Nations Convention on the Law of the Sea, they found no specific text for what happens when fish leave a country’s Exclusive Economic Zone (EEZ), a zone established to give a country national jurisdiction over a fishery resource.

That means countries could be vulnerable to economic losses, and those potential losses could make the fish populations themselves vulnerable as well.

“We realized there was an incentive for countries when they lose a fish or anticipate that loss to go ahead and overfish before it leaves because otherwise, they don’t get the monetary benefits of the resource,” said Oremus.

Read the full story at PHYS.org

Global fisheries could still become more profitable despite global warming

August 30, 2018 — Researchers from Japan’s Hokkaido University, the University of California, Santa Barbara (UCSB), National Center for Ecological Analysis and Synthesis, and Environmental Defense Fund  (EDF) found that harvesting sustainable amounts of seafood globally over the next 75 years can lead to higher total food production and profits, even taking into consideration the fish populations which are projected to decline as the ocean warms and habitats change.

This is because, under what has been determined as the best management scenario, some major fish and shellfish stocks that are commercially harvested, broadly referred to as fisheries, will grow and become more profitable, offsetting the many others projected to shrink or even disappear. On a global average, profitability could rise by 14 billion USD and harvest by 217 million metric tons above today’s levels, according to the study.

There is a catch. In the model, the growth was achieved under the projected moderate warming of 2.2°C (3.9°F) above average global temperatures by 2100. But if temperatures rise further, global fish harvest and profits are expected to decline below today’s levels even with the best management in place.

The researchers say their study, published in Science Advances, conveys an important message: the oceans can continue to be a source of healthy seafood and sustainable livelihoods for billions of people, but only if action is taken to manage the stocks well and limit the carbon emissions that drive climate change.

Read the full story at Science Daily