Inter-rater reliability of categorical versus continuous scoring of fish vitality: does it affect the utility of the reflex action mortality predictor (RAMP) approach?

Scoring reflex responsiveness and injury of aquatic organisms has gained popularity as predictors of discard survival. Given this method relies upon the individual interpretation of scoring criteria, an evaluation of its robustness is done here to test whether protocol-instructed, multiple raters with diverse backgrounds (research scientist, technician, and student) are able to produce similar or the same reflex and injury score for one of the same flatfish (European plaice, Pleuronectes platessa) after experiencing commercial fishing stressors. Inter-rater reliability for three raters was assessed by using a 3-point categorical scale (‘absent’, ‘weak’, ‘strong’) and a tagged visual analogue continuous scale (tVAS, a 10 cm bar split in three labelled sections: 0 for ‘absent’, ‘weak’, ‘moderate’, and ‘strong’) for six reflex responses, and a 4-point scale for four injury types. Plaice (n = 304) were sampled from 17 research beam-trawl deployments during four trips. Fleiss kappa (categorical scores) and intra-class correlation coefficients (ICC, continuous scores) indicated variable inter-rater agreement by reflex type (ranging between 0.55 and 0.88, and 67% and 91% for Fleiss kappa and ICC, respectively), with least agreement among raters on extent of injury (Fleiss kappa between 0.08 and 0.27). Despite differences among raters, which did not significantly influence the relationship between impairment and predicted survival, combining categorical reflex and injury scores always produced a close relationship of such vitality indices and observed delayed mortality. The use of the continuous scale did not improve fit of these models compared with using the reflex impairment index based on categorical scores. Given these findings, we recommend using a 3-point categorical over a continuous scale. We also determined that training rather than experience of raters minimised inter-rater differences. Our results suggest that cost-efficient reflex impairment and injury scoring may be considered a robust technique to evaluate lethal stress and damage of this flatfish species on-board commercial beam-trawl vessels

Short-term stress and mortality of juvenile school prawns, 'Metapenaeus macleayi', discarded from seines and trawls

Two experiments were carried out to assess the short-term impacts to juvenile school prawns, 'Metapenaeus macleayi' (Haswell) discarded from commercial seining and trawling in New South Wales, Australia, and the potential utility of modifications to operational and/or onboard handling practices designed to improve survival. For both gears, discards were handled according to two general categories of treatment (termed mild and extreme) chosen to represent the plausible limits of severity during existing commercial operations. A total of 600 trawled and 480 seined school prawns (from both treatments), along with appropriate numbers of controls (previously collected and housed in acclimation tanks), were placed into cages (in groups of 10). Subsets of each of these groups were then destructively sampled over periods of up to 5 days and examined for their mortality and physiological response (measured as levels of l-lactate in the haemolymph). In both experiments, the temporal mortalities in the treatment groups ranged between 0% and 15% and, for the most part, were not significantly different to controls. Prawns in the treatment groups had similar, significantly elevated levels of l-lactate approximately 40 min after being caught, but these returned to levels approaching baseline estimates within 48 h. Under the conditions examined, juvenile school prawns appear capable of withstanding a range of stressors associated with being discarded from active gears, and their fate is not greatly influenced by the duration of gear deployment and subsequent air exposure. However, further work is required to quantify other sources of unaccounted fishing mortality and, ultimately, the impacts that discarding has on stocks

Damage and partitioned mortality of teleosts discarded from two Australian penaeid fishing gears

Six field experiments were performed to (1) quantify the scale loss and partitioned (immediate and short-term) mortality of key teleosts discarded from a penaeid seiner and trawler operating in 2 estuaries in southeastern Australia, and (2) assess the utility of modified operational and/or onboard handling procedures for maximising survival. For both gears, several non-target species were caught, handled and discarded according to 2 general categories of treatment ('mild' and 'extreme') representing the plausible limits of severity of commercial operations. The mild treatments involved the shortest conventional deployments of the gears followed by the immediate sorting of catches in water-filled trays, while the extreme treatments comprised the longest conventional deployments and sorting in dry trays. Discards were examined for immediate mortalities and scale loss before sorting onboard, while live individuals of key species, along with appropriate numbers of controls, were released into sea cages and monitored for mortalities up to 5 d. For both gears, there was a trend of higher percentages of immediate mortalities in the extreme treatments, and more scale loss from dead than live seined and trawled silver biddy 'Gerres subfasciatus', seined tarwhine 'Rhabdosargus sarba' and trawled yellowfin bream 'Acanthopagrus australis'. Despite considerable interspecific variabilities, few intraspecific differences were detected between treatments for the short-term mortalities of live discards; however, for all species, these deaths were greater than those incurred by the controls (most of which survived). The partitioned mortality estimates were combined to provide a range of total mortalities for seined (95.97 and 99.07%, respectively) and trawled (71.74 and 97.64%) G. subfasciatus, seined R. sarba (23.95 and 100%) and trawled southern herring 'Herklotsichthys castelnaui' (100%) and 'A. australis' (3.40 and 35.01%). Because most deaths occurred irrespective of onboard handling procedures, we conclude that simply reducing the duration of gear deployments would provide a first step toward mitigating discard mortality in these fisheries

Repeatability of flatfish reflex impairment assessments based on video recordings.

Using measures of reflex impairment and injury to quantify an aquatic organism's vitality have gained popularity as survival predictors of discarded non-target fisheries catch. To evaluate the robustness of this method with respect to 'rater' subjectivity, we tested inter- and intra-rater repeatability and the role of 'expectation bias'. From video clips, multiple raters determined impairment levels of four reflexes of beam-trawled common sole (Solea solea) intended for discard. Raters had a range of technical experience, including veterinary students, practicing veterinarians, and fisheries scientists. Expectation bias was evaluated by first assessing a rater's assumption about the effect of air exposure on vitality, then comparing their reflex ratings of the same fish, once when the true air exposure duration was indicated and once when the time was exaggerated (by either 15 or 30 min). Inter-rater repeatability was assessed by having multiple raters evaluate those clips with true air exposure information; and intra- and inter-rater repeatability was determined by having individual raters evaluate a series of duplicated clips, all with true air exposure. Results indicate that inter- and intra-rater repeatability were high (intra-class correlation coefficients of 74% for both), and were not significantly affected by background type nor expectation bias related to assumed impact from prolonged air exposure. This suggests that reflex impairment as a metric for predicting fish survival is robust to involving multiple raters with diverse backgrounds. Bias is potentially more likely to be introduced through subjective reflexes than raters, given that consistency in scoring differed for some reflexes based on rater experience type. This study highlights the need to provide ample training for raters, and that no prior experience is needed to become a reliable rater. Moreover, before implementing reflexes in a vitality study, it is important to evaluate whether the determination of presence/absence is subjective

The European Landing Obligation. Reducing Discards in Complex, Multi-Species and Multi-Jurisdictional Fisheries

This open access book provides a comprehensive examination of the European Landing Obligation policy from many relevant perspectives. It includes evaluations of its impacts at economical, socio-cultural, ecological and institutional levels. It also discusses the feasibility and benefits of several potential mitigation strategies. The book was timely published, exactly at the time where the Landing Obligation was planned to be fully implemented. This book is of significant interest to all stakeholders involved, but also to the general public of Europe and to other jurisdictions throughout the world that are also searching for ways to deal with by-catch and discard issues

Maximising the survival of bycatch released from commercial estuarine fishing gears in New South Wales

In addition to the targeted catches, commercial fishers commonly catch other unwanted organisms (collectively termed 'bycatch') that are then discarded. Combined with the process of capture, such discarding may cause harm to individuals and ultimately affect entire populations. In response to concerns over such negative impacts, the aims of this study were to: (1) identify key factors and quantify their effect on the fate of key discards from seines, trawls, and gill nets used in southeastern Australian estuaries; and (2) test the utility of a range of operational and post-capture handling modifications designed to maximise survival. Five manipulative field (in the Wallis Lake and Clarence River estuaries), and two laboratory experiments (in Coffs Harbour) were completed to measure the effects of the deployment duration, configuration, and entanglement of gears, and air exposure on the stress, damage, and immediate and short-term mortality of discarded penaeids and teleosts. In the field, a total of 112 deployments were completed, with 21 species assessed for their post-capture condition. A random sub-sample of 5 950 penaeids was retained, and immediate mortalities of 81 589 teleosts landed on deck were determined, before representative sub-samples were monitored in purpose-built underwater cages, together with controls, a

Reducing discard mortality in an estuarine trawl fishery

A purpose-built, water-filled sorting tray was compared against a conventional dry tray for its utility in reducing discard mortality across a range of conditions in an Australian estuarine penaeid-trawl fishery, including the limits of typical delays in starting sorting (2 vs. 15 min). During nine days of fishing, up to 10 replicate deployments were done for each sorting method and delay. Bycatches (44 389 teleosts comprising 15 species) were assessed for their immediate mortalities, before 1346 live individuals (10 species) were released (to simulate discarding) into replicate cages and monitored for their short-term mortalities over five days. Appropriate controls were included for the most abundant economically-important species, yellowfin bream, 'Acanthopagrus australis'. Most trawled-and-discarded teleosts followed a pattern of minimal differences in immediate mortalities between sorting methods for the short delay, but generally fewer deaths in the water tray than in the conventional tray during the longer delay. However, owing to a dominant and slightly protracted influence of the trawling process, comparable rates of deaths were observed for caged fish irrespective of their post-capture treatment. Mixed-effects logistic models applied to four key species ('A. australis'; silver biddy, 'Gerres subfasciatus'; southern herring, 'Herklotsichthys castelnaui'; and Port Jackson glassfish, 'Ambassis jacksoniensis') revealed that in addition to the method and delay in sorting, the weights of total catch and jellyfish, salinity and the size of fish also had significant impacts on mortality. For the longer delay in sorting in the water tray, the influences of some of the other factors were negated so that total mortalities of three of the modelled species were reduced by almost one quarter. We conclude that while unaccounted fishing mortality can be reduced via changes to onboard sorting procedures, this approach should only be applied ancillary to efficient gear selectivity

Narrativas de Gênero-Relatos de História Oral: experiências de ítalo-brasileiros na Itália-contemporânea

Il libro si propone a pensare le dinamiche di integrazione e identità fra gli italo-brasiliani che decidono di vivere in Italia. Si pensa ad una dimanica di ritorno fondata sulle dinamiche mnemoniche che hanno creato un legame fra la realtà passata del fenomeno migratorio e il tempo presente, in cui le generazioni costituiscono un filo conduttore