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Incorporating a fish recruitment indicator into a health report card: A case study from Gladstone Harbour, Australia

Abstract The Gladstone Healthy Harbour Partnership (GHHP) was established in May 2012 to assess the health of Gladstone Harbour following public concern about a range of fish health issues that emerged in 2011. The GHHP is responsible for producing an annual report card on the health of the harbour that includes social, cultural, economic and environmental health indicators. Fish recruitment and fish health were identified as important measures to inform the fish and crab indicator group. The objective of this study was to determine suitable species and develop a fish recruitment indicator for incorporation into the health grading for Gladstone Harbour. Following a trial survey in 2014–15, Yellowfin Bream (Acanthopagrus australis) and Pikey Bream (Acanthopagrus berda) were selected for the development of a fish recruitment indicator. A total of 26 sites in 13 zones were selected as survey sites. Surveys were undertaken using a standardised castnet method that had previously been used for recruitment surveys. Surveys were undertaken in 2015–16 and 2016–17. Historic data from surveys from 2011 to 12 to 2013–14 at a number of sites were also assessed to provide historic gradings. A modelling strategy using a negative binomial distribution was used to determine the total juvenile Bream catch per visit to a site. Bream productivity was initially assessed as Year × Zone in 2015–16 and Year × Site in 2016–17 and then averaged to provide a zone and a whole of harbour score on a 0–1 scale. This was then converted to an A-E grading to ensure consistence with the other indicators. Based on the grading score Bream recruitment was assessed for the whole harbour as D (poor) in 2015–16 and B (good) in 2016–17. The results from the 2 years of surveys, the trial survey and the historic surveys confirmed that Bream recruits provide a suitable fish recruitment indicator for the Gladstone Harbour report card.

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Can fish really feel pain?

AbstractWe review studies claiming that fish feel pain and find deficiencies in the methods used for pain identification, particularly for distinguishing unconscious detection of injurious stimuli (nociception) from conscious pain. Results were also frequently misinterpreted and not replicable, so claims that fish feel pain remain unsubstantiated. Comparable problems exist in studies of invertebrates. In contrast, an extensive literature involving surgeries with fishes shows normal feeding and activity immediately or soon after surgery.Cfiber nociceptors, the most prevalent type in mammals and responsible for excruciating pain in humans, are rare in teleosts and absent in elasmobranchs studied to date. A‐delta nociceptors, not yet found in elasmobranchs, but relatively common in teleosts, likely serve rapid, less noxious injury signaling, triggering escape and avoidance responses. Clearly, fishes have survived well without the full range of nociception typical of humans or other mammals, a circumstance according well with the absence of the specialized cortical regions necessary for pain in humans. We evaluate recent claims for consciousness in fishes, but find these claims lack adequate supporting evidence, neurological feasibility, or the likelihood that consciousness would be adaptive. Even if fishes were conscious, it is unwarranted to assume that they possess a human‐like capacity for pain. Overall, the behavioral and neurobiological evidence reviewed shows fish responses to nociceptive stimuli are limited and fishes are unlikely to experience pain.

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Response to Torgersen et al. (2011): Reply to Diggles et al. (2011): Ecology and welfare of aquatic animals in wild capture fisheries

We welcome feedback on our paper that examined the ecology and welfare of aquatic animals in wild capture fisheries (Diggles et al. 2011), and agree with Torgersen et al. (2011) that the issue is an important one. However we must question statements such as ‘‘The basis for the interest in animal welfare is man’s capacity for empathy and the assumption or suspicion that animals have an experience of life.’’ We believe that interest in the welfare of animals in their natural environment should be founded on objective data, rather that anthropomorphic ‘‘empathy’’ and the vaguely founded ‘‘assumption or suspicion that animals have an experience of life.’’ This one example demonstrates how different people can interpret concepts of aquatic animal welfare in quite different ways, highlighting how views on these issues vary depending on external influences such as the culture, education, socio-economic status, dietary preferences, gender or even political and religious persuasion of the individuals involved (Furnham et al. 2003). As pointed out recently by Browman and Skiftesvik (2011), welfare issues blur the lines between science and ethics, morals and philosophy. As scientists publishing in a scientific journal, we believe the overriding constant that should be applied in the field to inform decision making is the scientific method, and therefore use of words that cannot be operationally defined, (such as empathy and experience) is incompatible with the scientific process. Instead, we consider the functional definition that an organism ‘‘is in good health with its biological systems (and particularly those involved in coping with challenges to stasis) functioning appropriately and not being forced to respond beyond their capacity’’ to be sufficient basis for interest in maintaining an animals welfare. Torgersen et al. (2011) challenged our statement that an implication of the nature based definition of welfare is that ‘‘[asphyxiation] may be an acceptable method of slaughter for commercial fishing if a nature based definition of welfare is used.’’ This is simply a reality of the nature based definition, and in stating ‘‘in that case the nature-based approach has little to offer’’ Torgersen et al. (2011) are encouraging a double standard by suggesting that some aspects of the nature This is the Rebuttal to the article, Torgersen et al. (doi:10.1007/s11160-011-9221-y).

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Ecology and welfare of aquatic animals in wild capture fisheries

The expansion of commercial aquaculture production has raised awareness of issues relating to the welfare of aquatic animals. The “Five Freedoms” approach to animal welfare was originally devised for farmed terrestrial animals, and has been applied in some countries to aquatic animals reared in aquaculture due to several commonalities inherent within food production systems. There are now moves towards assessing and addressing aquatic animal welfare issues that may arise in wild capture fisheries. However, all “five freedoms” are regularly contradicted in the natural environment, meaning this concept is inappropriate when considering the welfare of aquatic animals in their natural environments. The feelings-based approach to welfare relies on a suffering centered view that, when applied to the natural aquatic environment, requires use of value judgements, cannot encompass scientific uncertainty regarding awareness in fish, elasmobranchs and invertebrates (despite their unquestioned welfare needs), and cannot resolve the welfare conundrums posed by predator–prey interactions or anthropocentrically mediated environmental degradation. For these reasons, the feelings-based approach to welfare is inadequate, inappropriate and must be rejected if applied to aquatic animals in wild capture fisheries, because it demonstrably ignores empirical evidence and several realities apparent within the natural aquatic environment. Furthermore, application of the feelings-based approach is counterproductive as it can alienate key fisheries stakeholders, many of whom are working to address environmental issues of critical importance to the welfare, management and conservation of aquatic animal populations in their natural environment. In contrast, the function-based and nature-based approaches for defining animal welfare appear appropriate for application to the broad range of welfare issues (including emerging environmental issues such as endocrine disruption) that affect aquatic animals in their natural environment, without the need to selectively ignore groups such as elasmobranchs and invertebrates. We consider that the welfare needs of aquatic animals are inextricably entwined with the need for conservation of their populations, communities and their environment, an approach that is entirely consistent with the concept of ecosystem-based management.

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Following the chain to elusive anglers

AbstractObtaining reliable estimates of important parameters from recreational fisheries is problematic but critical for stock assessment and effective resource management. Sampling methodologies based on traditional design‐based sampling theory, is inadequate in obtaining representative catch and effort data, social or demographical characterization, or fisher behaviour from small hard‐to‐reach components within recreational fisheries (e.g. specialized sport fisheries) that may account for the majority of the catch for some species. A model‐based approach to sampling is necessary. Researchers in other disciplines including epidemiology and social sciences routinely survey rare or ‘hidden’ populations within the general community by penetration of social networks rather than by interception of individuals. We encourage fisheries researchers to rethink survey designs and consider the social elements of recreational fishing. Employing chain‐referral methods, such as respondent‐driven sampling (RDS), may be a statistically robust and cost‐effective option for sampling elusive sub‐elements within recreational fisheries. Chain‐referral sampling methodology is outlined and an example of a complemented ‘RDS‐recapture’ survey design is introduced as a cost‐effective application to estimating total catch in recreational fisheries.

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An improved technique for estimating short-term survival of released line-caught fish, and an application comparing barotrauma-relief methods in red emperor ( Lutjanus sebae Cuvier 1816)

Promotion of better procedures for releasing undersize fish, advocacy of catch-and-release angling, and changing minimum legal sizes are increasingly being used as tools for sustainable management of fish stocks. However without knowing the proportion of released fish that survive, the conservation value of any of these measures is uncertain. We developed a floating vertical enclosure to estimate short-term survival of released line-caught tropical and subtropical reef-associated species, and used it to compare the effectiveness of two barotrauma-relief procedures (venting and shotline releasing) on red emperor ( Lutjanus sebae). Barotrauma signs varied with capture depth, but not with the size of the fish. Fish from the greatest depths (40–52 m) exhibited extreme signs less frequently than did those from intermediate depths (30–40 m), possibly as a result of swim bladder gas being vented externally through a rupture in the body wall. All but two fish survived the experiment, and as neither release technique significantly improved short-term survival of the red emperor over non-treatment we see little benefit in promoting either venting or shotline releasing for this comparatively resilient species. Floating vertical enclosures can improve short-term post-release mortality estimates as they overcome many problems encountered when constraining fish in submerged cages.

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