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Key Scottish Environment Statistics 2003

wildlife

Status of BAP Species & Habitats: 1996-2001

Count

Biodiversity refers to the variety of life. A rich variety of species, habitats and ecosystems provides many of the essentials of life - water, food, clothing, medicines and relaxation.

In 1992, the UN Convention on Biological Diversity recognised the need to protect biodiversity. The UK was one of the 150 countries to sign up to the convention, and the UK Biodiversity Action Plan (UKBAP) was published to develop strategies to protect biological diversity. ² The Scottish Biodiversity Group (SBG) is responsible for implementing the objectives of the UKBAP in Scotland.

In Scotland, 184 species and 41 habitats are addressed by the UKBAP. Between 1996 and 2001, 92 (50%) of the species showed 'no change' or recovered to some degree, while 63 (34%) were 'in decline' or had been lost. All 16 species that are listed as 'lost' are believed to have had that status before the implementation of the UKBAP programme. ³ Figures for habitats indicate that just over half showed 'no change' or some signs of recovery. No habitats were lost, although 5 (12%) were declining.

SOURCE: SCOTTISH BIODIVERSITY GROUP

Mean number of vascular⁴plant species recorded

(*statistically significant, P<0.05)

Plant species diversity is one measure of botanical composition that can provide an indication of changes in habitat quality. Changes are often associated with land management and atmospheric pollution. Effects of climate change may become evident in the future.

The Countryside Survey 2000 ⁵ reported changes between surveys in 1990 and 1998 of 193 1km sample squares. Plant diversity, in terms of the number of vascular plant species recorded, was estimated from plots placed within each square.

No overall change was detected in the mean number of plant species recorded per square (a decline of 0.6% was not statistically significant). There were no changes within most broad habitats, including the arable and horticultural broad habitat, which is subject to a high degree of year-on-year disturbance. Significant changes in plant diversity were observed only in acid grassland and dwarf shrub heath.

An estimated 6.9% increase in plant diversity in acid grassland was in part due to an increased abundance of plant species associated with less acid conditions. An estimated 6.6% decrease in the species richness of dwarf shrub heath was associated with a decline in the prevalence of stress-tolerant plant species associated with low-nutrient conditions. This was partly offset by an increase in competitor plant species, which tend to benefit from heavy grazing or nutrient enrichment.

SOURCE: COUNTRYSIDE SURVEY 2000, SCOTTISH NATURAL HERITAGE

Species with at least 10% change in population

During the autumn and winter, Scotland's wetlands support important populations of breeding waders. Most waders are highly mobile, capable of responding rapidly to changes in the environment which might affect feeding or breeding behaviour. For example, weather conditions may affect count data for a particular species. Trends may therefore indicate a redistribution of populations rather than a decrease or increase.

The Wetland Bird Survey ⁶ provides reliable population indices on 11 out of 18 wader species wintering in Scotland. Comparing the mean population during two five-year periods, 1969-1973 and 1995-1999, shows that six of the 11 species increased by at least 10%. The grey plover showed the biggest rise in population, increasing by 538% during the period. Only one species fell by over 10%. The knot population decreased by 43% between 1969-1973 and 1995-1999. Four of the species showed little change over the period.

The UK is bound by international laws to protect and conserve waders, and the wetlands on which they depend. These include the Ramsar Convention on Wetlands, the EC Birds Directive (79/409/EEC and amendments) and the EC Habitats Directive (92/43/EEC).

SOURCE: WETLAND BIRD SURVEY ⁶

Estimated population⁷(thousands)

The Scottish coastline contains internationally important seal populations. An estimated 38% of the world population of grey seals, Halichoerus grypus, breeds in British waters ⁸. The Scottish population of this species is of particular conservation importance, as over 90% of the UK's grey seals are found around Scotland.

At the start of the 2001 pupping season, there were an estimated 125,100 grey seals in the waters of Scotland and eastern England, ⁷ an increase of 180% since 1984. This has been achieved through an average population increase of approximately 6% per year. Since 1997, the rate of increase has slowed to 5.6% per year. ⁸

The grey seal is protected under the Conservation of Seals Act 1970, which makes it an offence to take or kill any grey seal, except under licence in certain circumstances, between 1 September and 31 December each year. This coincides with the pupping season when the seals are at their most vulnerable. The grey seal also receives some protection from cruelty under the Wild Mammal (Protection) Act 1996 and is listed as a protected marine species in the EC Habitats Directive (92/43/EEC).

SOURCE: SEA MAMMAL RESEARCH UNIT

Numbers caught (thousands)

The salmon fishing industry is a significant economic and leisure resource in rural Scotland. To protect this resource sustainable management practices are essential. Climate change, water pollution, predation and disease may affect populations. Yearly variations in weather, timing of runs and fishing effort can affect catch sizes. So, a difference in catch does not necessarily indicate a difference in the abundance of the stock that provides the catch.

Catch sizes for the fixed engine and net & coble fisheries have fallen by 87% and 95% respectively since 1952. Catches rose during the 1950s and 1960s but have declined rapidly since the early 1970s. It should be noted that the fishing effort has declined at a similar rate, with effort for 2001 being less than 10% of that for 1952 for both fisheries.

Catches by rod & line have remained relatively steady over the period 1952-2001. Since 1994, salmon that have been caught and released by anglers have been reported separately. In 2001, 45,000 salmon were retained and 28,000 released. No figures for fishing effort for the rod & line fishery are available.

The Salmon Act 1986, as amended by the Salmon Conservation (Scotland) Act 2001, contains terms for the conservation and sustainable management of salmon fisheries in Scotland. For example, through provisions for setting weekly and annual close times and defining the fishing method that may be used.

SOURCE: FRESHWATER FISHERIES RESEARCH SERVICE ¹²

Estimated SSB and Bpa (thousand tonnes)

The ecosystem of the seas around Scotland is affected by commercial fishing for many species. The status of fish stocks is monitored to estimate the spawning stock biomass (SSB) - the total weight of fish capable of spawning in any one year. The health of a stock is assessed by comparing the SSB with the 'safe biological limit' (Bpa). The International Council for the Exploration of the Seas provides advice on fishery management for many fish species.

A ban on herring fishing in the North Sea between 1977 and 1983 allowed the stock to recover from a collapse, caused largely by overfishing in the 1960s and 1970s. A decline in the early 1990s meant that further measures were introduced in 1996. The North Sea cod stock has been declining since the late 1960s. Despite regulatory measures, fishing pressure on cod has been high since the early 1980s and the SSB remains low. The increase in the North Sea haddock SSB in 2001 is mainly due to the exceptionally strong 1999 year class. Subsequent year classes are below average and it is expected that the SSB will decline to below Bpa in the short term at current fishing mortality rates. After a 20-year period of decline, the SSB of North Sea/ West of Scotland saithe has been increasing since the early 1990s.

SOURCE: FISHERIES RESEARCH SERVICES, ICES ¹⁴

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