Anthropogenic factors affecting European river lamprey Lampetra fluviatilis in the Humber River Basin, north-east England

Abstract

Anadromous lampreys have declined throughout the world due to damaging anthropogenic activities. This is particularly evident for the European river lamprey Lampetra fluviatilis, and studies in the Humber River Basin have shown that poor longitudinal connectivity (between their feeding and suitable spawning habitats) due to man-made barriers and their commercial exploitation for recreational angling bait, are potentially impacting upon this population.

The objectives of this thesis were two-fold. Firstly, to evaluate the efficacy of technical, conventional fishways for upstream migrating river lamprey, as the effectiveness of these fishways to provide free passage for lamprey at man-made barriers in the Humber and elsewhere in Britain is unclear. Secondly, to reassess the level of exploitation in the tidal Ouse, Humber River Basin, and investigate both the scale and structure of the lamprey bait market in Britain and the knowledge and attitudes of key stakeholders within the market, which so far remain unknown.

Passive Integrated Transponder telemetry revealed that two fishways of different technical designs, plain Denil and pool and weir, were extremely inefficient for river lamprey, with passage efficiencies of 0.0 and 5.0% and attraction efficiencies of 91.8 and 42.6%, respectively. Lamprey were significantly delayed, up to 150 days, at the Denil fishway and lamprey failed to pass despite re-entering fishways on up to 12 separate days.

Analysis of catch data suggests that there has not been a decline in the river lamprey stock in the Ouse, although up until 2009 (inclusive) the exploitation level may have been at least twice (~20%) the level reported previously. Telephone interviews of angling wholesale supplier and tackle shop managers in Britain revealed that c.9 tonnes of river lamprey were supplied to tackle shops and anglers in Britain between 2011-2012. It also revealed that the majority of lamprey were sourced from The Netherlands and Estonia. The vast majority of tackle shop managers were unaware of which species of lamprey they sold, where they originated from and whether they were threatened, although most (77%) said there should be a ban on the capture and selling of lamprey in Britain if they were considered to be threatened. Conversely, supplier managers were generally more knowledgeable about the lamprey they sold but were more indecisive over a ban.