Development and intercalibration of methods in nordic freshwater fish monitoring

Appelberg, Magnus; Berger, Hans Mack; Hesthagen, Trygve; Kleiven, Einar; Kurkilahti, Mika; Raitaniemi, Jari; Rask, Martti

doi:10.1007/bf00476862

Cited by 183 publications

(150 citation statements)

References 6 publications

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“…To address our second objective, both benthic and mesopelagic survey gill nets were deployed to sample fish populations (Appelberg et al, 1995;CEN, 2005;Smejkal et al, 2015). Each benthic net was 40 m long and 1.5 m high and composed of sixteen panels with mesh sizes ranging from 5.5 mm to 135 mm.…”

Section: Fish Sampling and Data Analysismentioning

confidence: 99%

Past, present and future of the fish community of Lake Orta (Italy), one of the world’s largest acidified lakes

2016

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Section: Fish Sampling and Data Analysismentioning

confidence: 99%

Past, present and future of the fish community of Lake Orta (Italy), one of the world’s largest acidified lakes

2016

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“…Additional fish samples were taken in August 2006 to estimate the size-structure of pikeperch with NORDIC multi-mesh survey gillnets. Each gillnet consists of twelve 1.5 × 2.5 m panels having mesh sizes of 5, 6.25, 8, 10, 12.5, 15.5, 19.5, 24, 29, 35, 43 and 55 mm (from knot to knot) (Appelberg et al, 1995). A total of 12 NORDIC nets were used in two sampling events in late August covering randomized locations in the lake.…”

Section: > Lake Sahajärvi and Pikeperch Samplingmentioning

confidence: 99%

Problems in managing a slow-growing pikeperch (Sander lucioperca(L.)) population in Southern Finland

Milardi

Lappalainen

Malinen

et al. 2011

Knowl. Managt. Aquatic Ecosyst.

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Key-words:management, maturity, pikeperch, stunted growth Local fishery managers in Lake Sahajärvi tried to increase pikeperch yields by increasing the minimum allowed mesh size from 45 to 60 mm and size limit from 37 to 40 cm. However, due to the slow growth of pikeperch these measures may not be reasonable. Here, pikeperch yields were modelled with an age and size-structured yield-per-recruit model as a function of mesh size. Besides yields, also the proportion of minimum landing size and immature pikeperch caught with a different mesh size were evaluated. The results showed that maximum yields per recruit can be obtained with a 44 mm mesh size corresponding to yields of about 180 kg per 1000 age 2 pikeperch while with 60 mm mesh size the estimated yields are only 46 kg. The share of immature pikeperch is only 0.4% in 44 mm mesh size nets due to very small average size at maturity (24.8 cm TL) of both sexes. Because the observed growth is slow (k = 0.11 and L ∞ = 65.28 cm TL) and the density of pikeperch (BPUE in NORDIC nettings = 1200 g·net −1 ) is high, the most reasonable management measure to improve growth and average size could be to radically decrease population density. RÉSUMÉQuestions de gestion d'une population de sandres (Sander lucioperca (L.)) à croissance lente dans le sud de la Finlande Mots-clés :gestion, maturité, sandre, croissance réduite Les gestionnaires locaux de la pêcherie du lac Sahajärvi ont essayé d'augmenter les rendements des captures de sandres en augmentant de 45 à 60 mm la taille minimale des mailles autorisées, et de 37 à 40 cm la taille minimale de capture. Toutefois, en raison de la lente croissance du sandre ces mesures peuvent ne pas être fondées. Dans cet article, le rendement des captures a été modélisé par un modèle de rendement par recrue dépendant de l'âge et de la structure en taille, fonction de la taille des mailles. En plus des rendements, les proportions de poissons de taille minimale et de poissons immatures attrapés par différentes tailles de maille ont été évaluées. Les résultats montrent que le rendement maximum par recrue est obtenu avec une maille de 44 mm correspondant à des rendements d'environ 180 kg par 1000 sandres de deux ans alors qu'avec des mailles Article published by EDP Sciences M. Milardi et al.: Knowl. Managt. Aquatic Ecosyst. (2011) 400, 08 de 60 mm le rendement estimé est seulement de 46 kg. La part de sandres immatures est seulement de 0,4 % dans les filets de maille de 44 mm en raison de la très faible taille moyenne à maturité (24,8 cm TL) des deux sexes. Parce que la croissance observée est lente (k = 0.11 et L ∞ = 65, 28 cm TL) et la densité des sandres (BPUE dans les filets NORDIC = 1200 g·filet −1 ) forte, la mesure de gestion la plus adéquate pour accroître la croissance et la taille moyenne serait de réduire fortement la densité de population.

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“…Two 5 m × 30 m multimesh gill nets (Nordic survey nets, Appelberg et al 1995) were used simultaneously to sample from the surface to near the bottom. Each nets was divided into 12 panels (5 × 2.5 m) with mesh sizes of 5, 6.25, 8, 10, 12.5, 15.5, 19.5, 24, 29, 35, 43, 55 mm (randomly distributed).…”

Section: Fish and Zooplankton Samplingmentioning

confidence: 99%

Discriminating the diel vertical migration of fish andChaoborus flavicanslarvae in a lake using a dual-frequency echo sounder

Knudsen

Larsson

2009

Aquat. Living Resour.

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-The diel vertical migration of fish and larvae of the phantom midge Chaoborus flavicans was studied using a combined 38 and 200 kHz echo sounder. Multi-mesh gill net was used to sample fish, and a Schindler-Patalas trap to sample Chaoborus. Oxygen and temperature profiles were also recorded. At 38 kHz, only fish were detected, without considerable interference from Chaoborus echoes. At 200 kHz, both fish and Chaoborus were detected and echoes from Chaoborus almost completely masked all fish echoes at night. During the day, Chaoborus remained hidden in an oxygen-poor refuge near the bottom. Tracks of fish diving into the Chaoborus refuge were observed on several occasions. At the onset of dusk, Chaoborus started to rise and by the time it was dark they were occupying the whole water column. Fish were found in patches in midwater during the day. In the dark, the fish were dispersed throughout the water column. Results suggest that a dual-frequency approach can be used to discriminate between fish and Chaoborus and to provide a rapid method for their selective monitoring.

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Development and intercalibration of methods in nordic freshwater fish monitoring

Cited by 183 publications

References 6 publications

Past, present and future of the fish community of Lake Orta (Italy), one of the world’s largest acidified lakes

Past, present and future of the fish community of Lake Orta (Italy), one of the world’s largest acidified lakes

Problems in managing a slow-growing pikeperch (Sander lucioperca(L.)) population in Southern Finland

Discriminating the diel vertical migration of fish andChaoborus flavicanslarvae in a lake using a dual-frequency echo sounder

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