Conservation of seagrass vital for Worlds biggest fisheries

Rapid global population is increasing the demand for seafood. This is both a desire from communities of increased wealth to eat healthy food, as well as a daily nutritional necessity for many hundreds of millions of people. To deal with this demand we need to ensure that fisheries stocks are sustainably managed into the future. The problem is that policies and plans designed to make sure there are enough fish and invertebrates almost exclusively target fishing activity. But new research is showing how we also need to protect the critical habitats such as seagrass that are essential for the sustainability of these stocks and fisheries.

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May 21, 2018
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The majority of marine animals require more than a single habitat to live and thrive, and some specifies have specific habitat requirements to increase their chances of survival and the fitness of the population. For example Atlantic cod (Gadus morhua) spends its adult life shoaling in deep water where it lives, feeds and spawns. But juveniles require more stable habitat such as seagrass meadows. So, if we want to manage fish and invertebrate stocks for sustainability reasons, it is essential to protect the supporting habitats of targeted species. 

Seagrass meadows are just one of these critical habitats. Though it is clear that seagrasses are a vital part of ocean ecosystems, until now, there has been no information on the role that meadows play in supporting the productivity of world fisheries. We have now published the first quantitative global evidence on the significant roles that seagrasses play. Our latest research has determined that one-fifth of the world’s most landed fish, including Atlantic Cod and Walleye Pollack, benefit from the persistence of extensive seagrass meadows. This is because these species use seagrass as nursery habitat. Nursery grounds in seagrass meadows are a safer, less exposed, environment for eggs to be laid and young animals to find food and protection from predators as they grow. 
Our newly published research also finds that it is not just large scale fishing industries that benefit from the presence of seagrass meadows. Seagrasses are also exploited directly as a fishing ground. This is because they are an easily accessible fishing ground, small scale artisanal and subsistence fisheries around the world also use them. This includes fishers walking at low tide collecting invertebrates from these productive and extensive habitats. This is often done by women and children, and provides a source of essential protein and income for some of the most vulnerable people in tropical coastal communities.  It is a common and increasingly visible activity, but it is not usually included in fishery statistics and rarely considered in resource management strategies.
The coastal distribution of seagrass means that it is vulnerable to a multitude of threats from both land and sea. These include land runoff, coastal development, boat damage and trawling. Evidence is increasingly emerging of continued and extensive seagrass loss around the world.  The importance of seagrass meadows for fisheries productivity and hence food security is not reflected by the policies currently in place to protect these key habitats. Urgent action is needed if we want to continue enjoying the benefits that healthy and productive seagrass meadows provide. 
In our new research paper we explain how fisheries management must be broadened from just targeting fishing activity to also targeting the habitats on which fisheries depend. Awareness of the role of seagrass in global fisheries production -- and, so, food security -- must be central to any policy, and major manageable threats to seagrass, such as declining water quality, must be dealt with. Seagrass can be a resilient and supportive habitat -- but only if we take action to continue to enjoy the benefits it provides.


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Richard Unsworth

Lecturer in Marine Biology, Swansea University

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