Thursday, January 21, 2016

Which factors affect small-scale fisheries catch composition?

If you have been following our blog, you probably know by now how important small-scale fisheries are. Small-scale fisheries provide a host of social and economic benefits to communities, supporting their livelihoods through food security, nutrition quality, poverty alleviation, and maintenance of local cultures. Some studies have set their contribution to 25-50% of the global catch, supplying mostly food for local, national, and global markets.
    Small-scale fisheries are also important for providing jobs: they employ more than 90% of all the fishing workers in the world, which includes fishers, processors and small vendors, benefiting men and women alike. For being so important, one would think that these fisheries are highly valued by governments and societies, right? Not at all. They are usually forgotten when it comes to public policies. Besides, throughout the world many of these fisheries and communities that rely on them are at risk: overfishing (caused by themselves and/or by industrial fisheries), climate change and habitat loss contribute to the declining health of the oceans. To top it off, many small-scale fisheries lack good and reliable scientific information, meaning that most will not be subjected to any sort of management.
    The good news is that by understanding which factors influence fisheries, we can provide some basic information to support the management of fish populations and small-scale fisheries.
    In one of our new studies (Pennino et al. 2016), we proposed a new approach to understand the factors that affect small-scale fisheries and the composition of the species caught. The study highlights the need to include a spatial component in the analyses, after all, it is just intuitive to imagine that fishers will not choose their grounds by chance, since fish themselves are not distributed randomly. Even though we all knew that, we still needed to know how exactly this affected catch composition. Such understanding is essential to determine the proper spatial scale for management, and evaluate how different conservation policies may affect fishing economies.
    Our study applies this approach to two different types of small-scale fleets (coastal canoes x motorized larger boats) that operate off the Brazilian coastal states of Sergipe and Bahia, showing that a complex combinations of fishing, environmental and spatial factors affect what and how much of each species fishers catch. Environmental variables, such as depth and seabed, separate the groups of species for both fleet types. Gear, of course, also matters, but its relevance varies according to the fleet: it plays more of a role for coastal canoes. One of our most interesting findings is that the two types of fleet use the space in a complete different way, and that affects what they catch, even though they are all considered small-scale fisheries. This is important for showing that even within small-scale fisheries management, spatial decisions should not be uniform. For example, closing one area and not others have different impacts on distinct fleets and their associated catches and groups of fishers. Another interesting point we highlight in this study is that it makes more sense to have management focus on groups of species, instead of on key species, because catches are multispecific and integrative: if a fishers caught species A, it is very likely he will have also caught species B. Even if he lands only species A, there is a good chance that species B was simply discarded. 
    Again, we show the complexity of small-scale fisheries and the need to devote the time, attention and means to manage them properly, if we are to assure the diversity of fish we eat and the continuation of livelihoods of hundreds of fishing villages in Brazil and thousands in the world.

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