Galloway Fisheries Trust


Galloway Fisheries Trust



 

River Cree Rare Fish Project

The River Cree supports an important range of rare native fish. These are of high conservation status and most are protected under local and international legislation, as well as being listed as UK Biodiversity Action Plan species. These rare fish include sparling, allis shad, twaite shad, brook, river and sea lamprey, and spring running Atlantic salmon. The River Cree rare fish project will be used to find out more about these fascinating species and undertake various works that will result in their protection and enhancement.

Most of these fish are anadromous meaning they spawn in freshwater, but spend much of their adult lives at sea, thus good habitat in the river and access to it is vital for completion of their life-cycles. This three year project will run from 2009 to 2012 and is funded by GFT, Scottish Environment Protection Agency (SEPA), Scottish Natural Heritage (SNH), Forestry Commission Scotland (FCS), The Tubney Environmental Trust, The Esmée Fairbairn Foundation, Scottish Government, SWEAT and Crown Estates.

Esmée Fairbairn FoundationThe Tubney Charitable Trust

Sparling

Sometimes known as smelt, the sparling is a silver fish related to salmonids. Once numerous and supporting thriving fisheries, they have undergone severe declines in the U.K. The River Cree is now the only known population left on the West Coast of Scotland. However, nine populations were originally found just in the Solway in the Rivers Annan, Bladnoch, Cree, Dee, Esk, Fleet, Lochar, Nith and Urr. The reasons for these local extinctions include over-fishing, pollution and construction of barriers to migration.

Photograph of a River Cree sparling.
A River Cree sparling, the only known population left in the Solway.

Annual monitoring of sparling spawning in the River Cree is taking place as part of this project. While the population appears relatively healthy, any catastrophic event occurring during spawning has the potential to severely impact this sole sparling population. Due to this vulnerability of this population and the apparent absence of natural re-invasion, translocations to the Water of Fleet, a river of former occurrence, are being attempted. In 2010 a large number of females were stripped into water of Fleet and the eggs fertilised by multiple males. It is hoped that if this translocation has been successful adult fish will start migrating up the Water of Fleet in 2012 / 2013. However, additional translocations will be attempted annually during this project.

Photograph of the sparling spawning shoals.
Images of the sparling spawning shoals were captured using the Trust’s Remote Operated Vehicle.

In addition to this work, the area where these fish spawn in the River Cree is currently infested with an alien plant species Japanese knotweed. This plant adversely affects the spawning runs of this and other anadromous species and causes bank erosion, thus a program of eradication is being carried out in riparian sections of the Lower Cree (see the news archive for more information).

Allis and Twaite Shad

Shad are silver fish that are closely related to herring, although they can reach lengths of 40 or 50cm. These are extremely rare fish, although like sparling they used to be common and targeted by fisheries. Although both species of shad can be found off much of the UK coast, only one spawning population of allis shad is known in the UK in the River Tamar on the south coast of England and only a handful of spawning populations of twaite shad are found in England and Wales.

Photograph of Shad fish.
Shad captured for research purposes in nets close to the Cree estuary by Walter Davidson.

While no known spawning grounds for either species of shad occur in Scotland, gravid allis and twaite shad are captured in the Solway Firth, and Wigtown Bay in particular. Spent twaite shad are also captured (allis shad die after spawning) and hybrids between the two are caught. This strongly suggests both these fish are spawning in Wigtown Bay, possibly in the same area. It is interesting that no spawning behaviour has been observed locally. These fish are famous for their vigorous and noisy spawning which involves splashing on the water surface. This is why, although many shad populations spawn many kilometres up a river it is believed that these shad species are probably spawning in an upper estuary since they would be conspicuous in most rivers in the area.

Photograph of Shad stomach contents.
Processing of caught shad involves looking at stomach contents
and weighing the gonads to assess spawning condition.

The River Cree estuary is considered a candidate site due to shad captured in the vicinity by salmon nets. In 2010 potential spawning areas were accessed by boat and kick-sampling for shad eggs took place. No eggs were found, but this work is planned to continue in June / July annually when these fish spawn. The aim is to provide confirmation of the presence of spawning and allow subsequent protection for these extremely rare fish.

Brook, River and Sea Lamprey

Lamprey are among the oldest living vertebrates, and play an important role in the trophic ecology of a healthy river system. The larvae of all species, called ammocoetes, live in areas of silt or sand in freshwater and filter-feed for up to seven years before metamorphosis. However, lampreys are most famous for the parasitic adult stages of river and sea lamprey, which feed on fish usually for one or two years causing round lamprey scars.

Photograph of Larval lamprey known as ammocoetes.
Larval lamprey known as ammocoetes, filter feed from silt beds.
It is almost impossible to distinguish between species at this life stage.

There are three species of lamprey in the UK. Brook lamprey are the smallest, usually around 15cm, do not feed as adults and mature without ever leaving the river. River lamprey are usually around 30 cm in length. The transformers migrate downstream they feed on fish, usually in estuaries and coastal waters, before migrating back to freshwater. Both these lamprey tend to spawn in groups in April / May. Sea lamprey can grow up to 1m in length. After migration downstream they feed on fish in coastal and offshore waters. These then migrate back into freshwater and tend to spawn in pairs in June / July.

Photograph of Lamprey transformers
Lamprey transformers become adapted to migration to the spawning
grounds or to the sea to feed, depending on the species.

The River Cree rare fish project is attempting to map important lamprey habitats in the River Cree. All these lamprey build redds in areas of gravel and pebbles, into which they deposit their eggs. This work involves surveys for spawning lamprey and help has been asked from local river users who might observe this. Areas of silt and sand are also important habitat for the larval lamprey and electrofishing will be used in summer 2011 to find out where ammocoetes are located. In addition trapping of adult lamprey in the lower Cree will help to tell us when lamprey are migrating into the Cree and tell us how numbers are changing over time.

Photograph of Sea Lamprey
The largest of the British lamprey become mottled in colour
when returning to freshwater to spawn.

Spring-running Atlantic Salmon

These are an important sub-population of the Atlantic salmon in the River Cree. Atlantic salmon have been affected by barriers to migration, but more importantly by acidification in the High Cree (headwater area of the river), their historic spawning and nursery area. Acidification is caused by air pollution which has been deceasing over the past few decades, however, due to the geology of Galloway and extent of commercial forestry cover, recovery has been very slow. Periodic ‘acid-flushes’ during high flows mean that salmon spawning is not successful throughout all but the lowest sections of the High Cree.

Photograph of a Spring salmon.
Release of a spring salmon caught in the lower Cree.

In 2010, one of the barriers to migration, a dam on the Clauchrie Burn was modified to allow fish passage. The Cree Valley Community Woodland Trust (CVCWT) and FCS are working to clear riparian areas of sitka conifers close to the High Cree burns. However, even with this work and the reduction of air pollution, salmon recovery in the High Cree is likely to take decades to occur naturally.

As part of the Rare Fish Project, limestone gravel addition which aims to locally improve the survival of the most sensitive life stages of salmon, is being trialled. The eggs and newly hatched alevins which live in the spawning redds are most adversely affected by acid, the addition of limestone gravel provides a refuge from acid flushes. When juvenile salmon emerge from the gravel as fry they are more able to cope with acidified waters, as shown by the survival in the High Cree of stocked salmon fry. If these two years of trials are successful it is envisaged that limestone gravel would be added to areas in the lower to mid areas of the High Cree where salmon are attempting to spawn, but where this natural spawning is not successful. It is hoped that this will speed up the recovery of High Cree spring salmon.

Photograph of Limestone gravel being added to the trial site.
Limestone gravel being added to the trial site. If this is successful the
trials will be expanded to test this liming method in different locations.

 

Galloway Fisheries Trust