Broads Uncovered: Fish

In the U.K. freshwater habitats comprise about 12% of our total land surface and are home to 42 species of native freshwater fish, 29 of which occur here in the Broads National Park. Angling (fishing) contributes around £100 million to East Anglia’s tourist industry each year – the sale of rod licenses alone brings in nearly £3 million.

Freshwater Fish Matter

According to the Environment Agency the Broads National Park is arguably one of the most important natural freshwater fishery resources in the U.K. However, many local children, when asked to name what types of fish live in the nearby rivers or broads, list a range of marine or tropical fish from clown fish (Nemo), snake head fish (at least it lives in freshwater) to salmon, cod, tuna, sharks and herring! Only occasionally does the word pike pop up. Admittedly part of the problem is the difficulty of seeing what’s underwater, so the assumption is often “nothing much”! Added to this is that the majority of nature programs on TV focus on the “more exciting” wildlife to be found in the sea and abroad.  It’s imperative to raise awareness of the fish that live in the Park’s 6 rivers, 63 broads and myriad of dykes to not only safeguard the area’s lucrative fishing industry but also to ensure these habitats are kept in a good condition. Especially as the Broads National Park’s freshwater habitats are the source of our drinking water!

Changing Water Quality

Historically the waterways (rivers, broads and dykes) of the Broads National Park abounded with fish, not only in terms of numbers (it was considered normal to catch 75kg of fish in a day’s fishing) but also variety of species. The water was clear and full of plankton and aquatic plants providing food, shelter and safety from predators for zooplankton, invertebrates and fish. Sadly, since 1900 these conditions have changed as the impact of overfishing (before 1870 there were no regulations), pollution, increased motor boat activity, sedimentation and loss of habitat from the complete drainage of marshes took their toll. The result has not only been a decline in the overall abundance of fish in the system but also the favouring of species, such as bream and roach, that can cope with the new conditions (turbid waters, algal blooms, loss of aquatic plants and animals such as leeches, molluscs, and snails) over those such as perch and rudd.

The Role of Science

In order to counter these threats, we need to understand the ecology of the Broad’s freshwater habitats – the interactions between the animals and plants and environmental factors such as pH, salinity, temperature and toxins. With this knowledge organisations such as the Environment Agency, Broads Authority, Wildlife Trusts and others are better able to manage and protect the freshwater habitats as well as undertake large scale projects to restore those that have been degraded by a combination of human actions. The £4.5 million Hoveton Great Broad Restoration Project is currently underway building on knowledge from previous  restoration projects such as those at Cockshoot Broad and Ormesby Broad.

New Research Tracking Fish in the Park

The Broads National Park is unique in Britain as its 200km of waterways are clear of all barriers to movement such as dams, weirs and locks – great for boating enthusiasts and as it turns out fish scientists! Emily Rose Winter has been conducting the first large scale fish tracking study ever to be done in the Broads National Park for her PhD. She has been investigating the movement of pike and bream in the Bure, Thurne and Ant river valleys and loves the fact that the lack of barriers means it’s possible to study the fish behaving “normally”. By normally she means they are able to move unrestricted throughout the system to find food, breed, escape predators and in response to changing environmental factors such as temperature. In other parts of the country the fish’s behaviour will be modified by barriers such as dams and locks restricting where and how far they can go.

This Prezi Presentation showcases our interview with Emily Rose Winter and our 5 favourite fish found in the National Park.

One way the data generated by Emily’s research could be used is to help organisations protect fish from threats such as saltwater. Not all fish are able to live in salt water and freshwater fish range in their ability to tolerate salt in their environment. Some freshwater fish like the three-spined stickleback have no problems while others, like pike and bream, will die if the salinity becomes too high and they cannot escape. The proximity of the sea to the Broads National Park and the tidal nature of its rivers means that the salinity of the water frequently fluctuates – the degree to which it does varies with location. For example, salinity is high in the estuarine conditions of Breydon Water and low to non-existent in the upper reaches of the Bure, Thurne and Ant rivers. However, with climate change and rising sea levels the frequency with which salt water extends into the upper reaches of the Park’s river valleys is set to increase. Understanding where fish go and what they do when salinity levels fluctuate will help put measures, like the barrier at Potter Heigham, in place to protect them.

Many thanks to Mark Barrow at Beneath British Waters and Emily Rose Winter for allowing us to use their lovely fishy photos!

 

For more great short videos of of fish in the River Yare and Wensum and other wildlife in the Broads National Park check out the A Shot of Wildlife Youtube channel.