2d859784b3836392e5b7e4205011c97c English dataset Carly Cassidy University Marine Biological Station (UMBS), Millport Millport KA28 0EG carlycassidy@hotmail.co.uk pointOfContact 2019-11-04 MEDIN Discovery metadata standard 2.3.8 4326 2000 UMBSM Clyde Sea The Fate of Discarded Invertebrates From The Clyde Nephrops Fishery 2000-11-01 publication UMBSM9439 A PhD was carried out at the University Marine Biological Station Millport (UMBSM) and presented to the University of London. The study assesses the composition and the fate of invertebrates which are regularly discarded in the Clyde Nephrops fishery. Philip Smith University Marine Biological Station (UMBS), Millport Millport KA28 0EG philip.smith@millport.gla.ac.uk originator Kathryn Stevenson University Marine Biological Station (UMBS), Millport Millport KA28 0EG kathryn.stevenson@millport.gla.ac.uk custodian notPlanned Documents Marine Environmental Data and Information Network Species distribution GEMET - INSPIRE themes, version 1.0 2008-01-06 revision Fish and shellfish catch statistics Fish disease and parasites Fishing by-catch SeaDataNet P021 parameter discovery vocabulary 2009-11-16 revision Permission to copy, or reproduce the contents of this report is granted subject to citation of the source of this material. otherRestrictions DASSH terms and conditions apply English biota Charting Progress 2 Sea Areas 2009-06-18 creation Irish Sea Charting Progress 2 Sea Areas 2009-06-18 creation Minches & Western Scotland -5.5151 -4.6198 55.2165 56.0107 1997-10-01 2000-06-01 Data Archive for Seabed Species and Habitats (DASSH) Data Manager 01752 633102 01752 633291 Marine Biological Association of the UK, The Laboratory, Citadel Hill Plymouth PL1 2PB dassh.enquiries@mba.ac.uk distributor dataset Data Specification on Species distribution - Draft Technical Guidelines 2013-02-03 publication See the referenced specification true North and south Clyde Sea areas were divided in to sectors according to an arbitrary line drawn between Troon and the northern tip of Holy Island. In order to assess catch and discard composition of Nephrops trawls, monthly survey trips were conducted on three local commercial trawlers and RV Aora (UMBSM) between October 1997 and October 1998. The south Clyde sea area was sampled quarterly. The whole catch was placed into standard fish baskets (44l) once hauled. Catch was sorted and sub-samples were collected randomly. The marketable fraction of the catch was weighed and measured is baskets. Catch composition was determined by subtracting the marketable proportion from the total catch volume. Sub-sample taxonomic composition was assessed to species (abundance and biomass). Fishing vessels utilised: RV Aora used a commercial 'rock hopper' otter trawl with 70mm diamond-shaped mesh and a 'clean' net. FV Red Baron used a commercial 'rock hopper' otter trawl with 70mm diamond-shaped mesh fitted with a square mesh panel in the cod-end and a 'clean' net with a tickler chain. FV Andrias operated a 'clean' net with a mesh size of 70mm and a groundrope with small discs and a tickler chain. FV Tricia Anne operated a twin-rigged net with a 225kg weight. Both nets were 'rock hopper' otter-trawls with 80mm diamond-shaped mesh which had a square mesh panel in the cod-end. Chain was also wound into the groundrope. Comparisons between total catch weight, discard weight and the weights of fish and Nephrops landed between the north and south Clyde sea area were conducted. Damage assessments of discarded invertebrates was conducted. The study aimed to assess the damage sustained by commercially important epibenthic invertebrates which are routinely discarded from Nephrops trawls. Samples of invertebrate discards were obtained from 42 trawls between the three commercial trawlers and RV Aora between November 1997 and August 1998. Sorting procedures varied between boats. Catch was sorted onto a sorting table/ conveyor belt and marketable catch was separated. Sub-samples of 60 invertebrate species were randomly collected from different parts of the catch and sorted into baskets (3l and 6l) prior to assessment. Baskets with starfish and brittlestars were filled with seawater. Size and visible damage of discard samples were determined within the laboratory. Sex was determined for squat lobsters and swimming crabs. The presence of regenerating limbs were noted. Damage was assessed on a four point scale (intact, mild, medium and severe damage) and expressed as a percentage frequency. The physiological stress of discarded decapod crustaceans (Munida rugosa and Liocarcius depurator) was assessed. The blood chemistry (pH, L-lactic acid, D-glucose and ammonia concentrations) of trawled and creel-caught crustaceans were compared. Samples were collected from RV Aora trawls (two 2h tows) of Fintray Bay. Ten randomly selected L.depurator and M.rugosa were transferred to shaded tubs of running seawater. Haemolymph samples (600 microlitres) were extracted from the arthrodial membrane with a 1ml syringe and a hypodermic needle (25G) within less than 6 minutes of hauling. Blood samples were taken from a second treatment group of 20 individuals per species per haul. Three days after trawling blood samples were collected from the control group of M.rugosa and L.depurator captured in baited creels. All blood samples were stored in Epindorf microtubes (1.5ml) in liquid nitrogen. Size and damage of individuals were recorded and blood samples were stored at -20 degrees Celsius. The pH of haemolymph was measured using a pH meter (Russel, RL150) with a pH electrode (Russel, TR/CMAW177/TB). 100 microlitres were utilised for an ammonia assay. The remainder was mixed with an equal volume of 0.6M perchloric acid (PCA) and centrifuged for 20min at 10 000g. Supernatant was neutralised with 2M potassium bicarbonate. The precipitated potassium perchlorate was centrifuged again after being cooled on ice for 10 minutes. The concentration of L-lactate in 50 microlitres of sample was determined by the methods stated in Engel and Jones (1978). D-glucose levels were determined by using the glucose oxidase technique (Boehringer-Mannheim, Cat. No. 124028.) in a microplate format as described by Webster (1996). Dissolved ammonia concentrations were measured using the flow injection/ gas diffusion method (Hunter and Uglow, 1993). Recovery experiments were conducted in October 1999. Haemolymph samples were obtained immediately from 6 randomly collected L.depurator from an RV Aora trawl (2h) south of Little Cumbrae Island (-74 CD). A second trial group (10 crabs) were exposed to air (1h). The remainder of animals were placed into shaded fish boxes (75 x 40cm) and supplied with running seawater. Haemolymph samples were taken from groups of 8-10 individuals at 0.5, 1, 2, 4, 6, 8, 12 and 24h intervals following aerial exposure. O return to laboratory, all crabs were housed in a communal outdoor holding tak (110 x 65cm). Measurements, sex and damage of individuals were assessed and recorded. Haemolymph samples were stored in liquid nitrogen as previously stated. Another experiment investigated the effects of exercise and aerial exposure. Fourteen L. depurator and 21 M. rugosa were caught by creel in Fintry Bay and held in separate holding tanks. Blood samples were take after one week. One week later 10 male L.depurator were exposed to air for 1 hour prior to haemolymph sampling. Trawl conditions were mimicked in a tank (60 x 37cm). A second group of crabs were constantly inverted and kept in motion using a pond net for 1h prior to haemolymph sampling. Samples were treated as previously stated. Water loss after aerial exposure was assessed (after 1h of exposure in individual wide necked jars at 10 degrees Celsius) by determining the percentage weight loss in tank held M. rugosa and L.depurator. Blood samples were assessed for osmolarity (freeze point depression, Roebling micro-osmometer type 12/12DR). Haemolymph was also collected from a submerged control group. Short and longer-term mortality of crustaceans were assessed. Short term mortality was assessed after trawling and exposed to air on deck for 16-90 minutes. Crabs were transferred to standard fish boxes (75 x 40 cm) with running seawater. Dead and live counts were conducted. Longer term survival of decapods was assessed in September 1999. Post trawling survival was monitored. Experimental animals were exposed to air for 90 minutes before placing them into fish boxes with running water. Creel caught M. rugosa and L. depurator were used as controls. A second treatment (90 minute exposure and retained in creels) was performed. A third treatment (hand removal of 1 cheliped and 1 pereiopod) was conducted. All animals were measured, sexed and transferred to individual plastic mesh containers and placed in creels. Creels were deployed at -40m CD in Fintry Bay where survival was monitored twice per week. Investigations into short and longer-term mortality of discarded echinoderms and buccinid gastropods was conducted. Short term mortality investigations were conducted as that previously stated for decapods. Live animals were distinguished by the following criteria: Asterias rubens: movement of tube feet; Ophiura ophiura: movement or arms, spines and mouth podia; whelks: retraction of foot and operculum after mechanical stimulation. Longer term mortality of haphazardly sampled invertebrates (A. rubens, O.ophiura, Buccinum undatum and Neptunea antiqua) was assessed. Individuals of various sizes and levels of damage were utilised. Selected animals were exposed for 90 minutes before placing them into fish boxes with running water. Individual A.rubens or whelks were transferred to plastic mesh containers and put into modified creels (-40m CD). O.Ophiura were transferred into outdoor holding tanks. Creel caught intact species were used as controls. Animals were placed into mesh bags and transferred into modified creels. Mortality of two groups were assessed weekly. Longer term mortality after trawl damage and induced autotomy was investigated using whelks and starfish. Samples were exposed to air for 90 minutes, before being stored in tanks. One group of O.ophiura were placed into tanks once hauled, while another group were exposed for 90 minutes. Brittlestars and whelks were housed separately within the laboratory. Star fish were placed into floating plastic mesh containers. Whelk and brittlestar mortality was recorded weekly over 21 days. Star fish were subject to further treatment (control, trawled, punctured, induced autotomy, 1 arm removed, 3 arms removed). Mortality was recorded on daily over three weeks. The righting time of A. rubens was assessed. One group was placed into a tank with running seawater immediately after hauling. One group was exposed to air for 1.5h. A control group was collected by SCUBA and placed into tanks with mud and running water. Individuals were placed with their oral surface exposed and the time it took for individuals to right themselves was recorded. Identification of pathogenic agents was conducted. Assessments of A. rubens lesions were conducted. Bacterial swabs were taken from lesions of trawled animals and the epidermis of healthy control animals. Swabs were plated on Zobells media and cultures at 20 degrees Celsius for 4 days and stored at 4 degress Celsius until required. Bacteria identification followed. Colonies were analysied using the Analytical Profile Index 10 S (API), which consisted of 12 biochemical tests using API 10 S strips. The utilization of discards by benthic scavengers was assessed. Sinking rates and utilization time was investigated. Sinking rate experiments were conducted at -3m CD at slack water and static water (aquarium 0.85m depth). Twenty individuals per species were selected (dead and defrosted). Utilization time was investigated via a baited time-lapse camera (TLC) (Kongsberg-Simrad Ltd., UK) which was deployed at -7m CD off Keppel Pier. The colour camera (OE1366) was fitted with a zoom lens and a modified surface control unit (OE1232) and a 30m cable (NC-13). A light utilizing a battery of far-red light-emitting diodes (lambda=615nm) was designed by Kongsberg-Simrad Ltd., UK. Images were recorded and monitired via a Sony TV and Panasonic S-VHS time-lapse VCR (no.AG6730). The camera was mounted on a Dexion angle-frame. A standardized bait bacth of trawler composition was placed at the base of the TLC by SCUBA. Utilization time and the succession of scavengers was recorded. The latter was achieved by SCUBA observations. Bait batches were placed in the centre of 6 replicate metal rings fixed with four legs which held the rings 20cm above substratum. Studies were conducted at Loch Sween at -15m CD. Dives were conducted at 2, 4, 6 and 24h intervals and scavengers and animals present were recorded. Experiments were utilized where scavengers were trapped in creels and funnel traps (-45m CD). Bait in creels contained L.depurator, M. rugosa, A. rubens and O. ophiura obtained from trawl experiments. Specimens were injured by punching a hole into each individual and transferred into velcro-sealed bait bags composed of plankton net (0.5mm mesh size) and stored in a freezer. Identical empty bait bags were used as controls. Two fleets of creels were shot. An additional trail was conducted in the south Clyde sea area at -45m CD and baited with Nephrops 'heads'. After 48 hours creels were lifted and megafauna present were recorded. Funnel traps were transferred into tanks at the laboratory and animals captured were preserved in ethanol within 2 days.