A Tale of Two Forage Fish: anchovies in Peru and sandeels in Scotland

Before joining RSPB Scotland, Oscar, our Marine Policy Officer worked on the other side of the world. In this blog he highlights some similarites between anchovies in Peru, and sandeels in Scotland, and why these wee fish play a huge role in our marine ecosystem.

I've had the privilege of working in marine conservation in Peru and now work for the RSPB in Scotland. Although Peru and Scotland are more than 6 thousand miles away on the map, they share some fascinating similarities in fish populations and their vital role in supporting the health of seabirds. 

Through my experiences, I've witnessed first-hand the importance of forage fish for the ocean and how managing these fisheries sustainably provides benefits for seabirds, the wider marine environment, and people. In Peru and Scotland, anchovies and sandeels respectively, are forage fish. These are not just any fish; they are key prey for many marine species including bigger fish, seals, seabirds, whales and dolphins which makes them the foundation of marine food chains. If the populations of these little fish drop it's bad news not just for bigger fish that we as humans like to eat, but also for other species which rely on them, including seabirds who use them to feed their chicks, helping them grow and thrive. Keeping seabirds thriving is important because they are great visual indicators of how healthy the ocean is, so more seabirds generally mean a healthier ocean ecosystem. That’s why it's worrying that here in Scotland numbers of breeding seabirds have declined by almost 50% since the 1980s.  It’s also important as Scotland is globally important for a number of seabirds including 56% of the world's breeding population of Great Skua, 16% of the Manx Shearwater and 46% of the Northern Gannet.  

Small fish swimming underwater

Camera Sandeels underwater. Small but important fish! Anne Bignall

Both anchovy and sandeel populations tend to fluctuate up and down a lot. Most of these swings are due to natural factors, like changes in the climate and ocean temperature. But fishing can also make these fluctuations worse. If we fish too much forage fish, which is usually used for fishmeal and fertilizer, or we don’t allow them to recover, we can affect the whole ocean food web. For instance, in the 1970s, the Peruvian anchovy fishery collapsed after reaching 12 million tons yearly (yes, that’s a lot! - technically the largest fishery in the world). The main cause was a combined effect of rising ocean temperature and too much fishing. This was hugely damaging to Peruvian seabirds. Species like the Peruvian Cormorant, Peruvian Pelican, and Peruvian Booby decreased by 41%, and many nesting grounds (where they lay eggs and rear their chicks) disappeared.  Here in Scotland, reduced sandeel numbers has been linked to population declines of seabirds. For example, the breeding abundance of Kittiwakes in Scotland in 2018 was 69% below the 1986 baseline where a reduction in sandeel availability is thought to have contributed to this and declines in other seabird populations that are dependent on sandeels such as Artic Terns, Puffins and Artic Skuas.  

A Puffin among pink flowers on the edge of a cliff.

Camera Puffins are one of Scotland's iconic seabirds. Ben Andrew

To address these declines (and to ensure they don’t happen again!), nowadays, Peruvian fisheries’ managers are working hard to ensure we're not overfishing these important fish by monitoring their numbers, fluctuations of sea temperature, and putting limits on how many can be caught. They are also setting regulations about when and where we can fish to protect these species. Here in Scotland the government recognises the vitally important role of sandeels for the benefit of our seabirds and other marine life and are currently consulting on a proposal to end industrial sandeel trawling in Scottish waters. This is an activity undertaken almost exclusively by EU trawlers and will have minimal impact on Scottish fishing vessels, but it makes good on the Scottish Governments longstanding commitment to protect sandeels and would help our seabirds. You can support an end to industrial sandeel trawling in Scotland by taking our e-action here.  

As noted, many seabirds are dependent on these tiny fish to feed themselves, and their chicks. Ending sandeel fishing would throw them a vital lifeline and help boost their survival in the face of mounting threats from other pressures including increasingly busy seas where they struggle to find safe places and plentiful food. 

My experience has undoubtedly taught me that taking care of forage fish is a big deal and should be a shared global effort in order to keep our seas healthy and ensure they're thriving for generations to come. Let's keep our oceans healthy and keep our seabirds thriving! 

Main image: Peruvian Pelicans on a rock. Shutterstock