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Swords, Ireland

There is a small international scientific literature, principally from North America, on recovery of fish communities following substantial fish kill events and a smaller literature on monetary assessment of losses in such events. A chemical discharge led to over 90% loss of brown trout (Salmo trutta L.) and Atlantic salmon (Salmo salar L.) age classes in 31km of the River Boyne catchment, a major Irish salmon-producing and angling fishery in July 1997. Subsequent investigations permitted a novel study that examined both the changes in the fish community composition over time and also a monetary assessment of losses. The population structure and density of 1[1] and older brown trout took four to five years to recover. The population of 1[1] salmon increased substantially during the recovery period, to levels threefold higher than those recorded prior to the pollution event. Financial loss assessment was examined through ‘replacement cost’ and through consequential loss models. An examination of the monetary modelling, in the light of the fish community recovery, showed there was an ecological justification for the potential loss model used. This approach to appraisal of loss is considered to have an international relevance, in the context of ecosystem processes and the ‘polluter pays’ principle. © ROYAL IRISH ACADEMY. Source

Krkosek M.,University of Otago | Revie C.W.,University of Prince Edward Island | Gargan P.G.,Inland Fisheries Ireland | Skilbrei O.T.,Norwegian Institute of Marine Research | And 2 more authors.
Proceedings of the Royal Society B: Biological Sciences

Parasites may have large effects on host population dynamics, marine fisheries and conservation, but a clear elucidation of their impact is limited by a lack of ecosystem-scale experimental data. We conducted a meta-analysis of replicated manipulative field experiments concerning the influence of parasitism by crustaceans on the marine survival of Atlantic salmon (Salmo salar L.). The data include 24 trials in which tagged smolts (totalling 283 347 fish; 1996-2008) were released as paired control and parasiticide-treated groups into 10 areas of Ireland and Norway. All experimental fish were infectionfree when released into freshwater, and a proportion of each group was recovered as adult recruits returning to coastal waters 1 or more years later. Treatment had a significant positive effect on survival to recruitment, with an overall effect size (odds ratio) of 1.29 that corresponds to an estimated loss of 39 per cent (95% CI: 18-55%) of adult salmon recruitment. The parasitic crustaceans were probably acquired during early marine migration in areas that host large aquaculture populations of domesticated salmon, which elevate local abundances of ectoparasitic copepods-particularly Lepeophtheirus salmonis. These results provide experimental evidence from a large marine ecosystem that parasites can have large impacts on fish recruitment, fisheries and conservation. © 2012 The Author(s) Published by the Royal Society. All rights reserved. Source

Baars J.-R.,University College Dublin | Coetzee J.A.,Rhodes University | Martin G.,Rhodes University | Hill M.P.,Rhodes University | Caffrey J.M.,Inland Fisheries Ireland

The non-native invasive plant, Lagarosiphon major (Hydrocharitaceae) is a submersed aquatic macrophyte that poses a significant threat to water bodies in Europe. Dense infestations prove difficult to manage using traditional methods. In order to initiate a biocontrol programme, a survey for natural enemies of Lagarosiphon was conducted in South Africa. Several phytophagous species were recorded for the first time, with at least three showing notable promise as candidate agents. Amongst these, a leaf-mining fly, Hydrellia sp. (Ephydridae) that occurred over a wide distribution causes significant leaf damage despite high levels of parasitism by braconid wasps. Another yet unidentified fly was recorded mining the stem of L. major. Two leaf-feeding and shoot boring weevils, cf. Bagous sp. (Curculionidae) were recorded damaging the shoot tips and stunting the growth of the stem. Several leaf-feeding lepidopteran species (Nymphulinae) were frequently recorded, but are expected to feed on a wide range of plant species and are not considered for importation before other candidates are assessed. The discovery of several natural enemies in the country of origin improves the biological control prospects of L. major in Europe. © 2010 Springer Science+Business Media B.V. Source

Hynes S.,National University of Ireland | O'Reilly P.,Inland Fisheries Ireland | Corless R.,National University of Ireland
Ecosystem Services

This paper compares recreational fishing travel cost demand modelling results from an on-site angler intercept survey to results from a household survey where the respondents represent the same underlying population of interest. We employed a Poisson and negative binomial count data model with and without the econometric corrections for the on-site sampling issues of endogenous stratification and truncation as the onsite modelling approach and use Poisson and negative binomial count data hurdle specifications to control for excess zeros in the household modelling approach. We find that welfare estimates differ substantially across the two samples and argue that the underlying samples may represent two different types of anglers. © 2015 Elsevier B.V. Source

Gargan P.G.,Inland Fisheries Ireland | Stafford T.,Inland Fisheries Ireland | Okland F.,Norwegian Institute for Nature Research | Thorstad E.B.,Norwegian Institute for Nature Research
Fisheries Research

The practice of catch and release (C&R) in salmon rod fisheries has become increasingly common due to the widespread decline in salmon abundance in the North Atlantic over the past two decades. Many Irish Atlantic salmon rivers are only open for catch and release (C&R) angling since a change in salmon management in 2006. Success of Atlantic salmon surviving to contribute to the spawning stock following C&R was studied in three rivers. In total, 76 fish were tagged with radio transmitters post C&R angling. Survival to spawning was greater for fly caught (98%) than lure caught fish (55%). Hence, survival after C&R was dependent on gear type. Hook location may have influenced C&R mortality in the lure captured fish. All fish bleeding at the hook wound or hooked in the throat died. Simultaneous hooking in the upper and lower mouth may also have contributed to reduced survival. There was an overall net upstream movement post release with many salmon moving more than 10. km upstream. Results demonstrated that, when conducted using proper guidelines, survival of salmon after C&R can be high. Opening rivers to C&R angling can be successful as a tool to provide information on salmon stock status while not significantly impacting on salmon survival. © 2014 Elsevier B.V. Source

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