1 University of Otago – Dunedin, New Zealand
2Waikato Regional Council – 401 Grey Street, Hamilton, New Zealand
3University of Waikato – Hamilton, New Zealand
4Hawkes Bay Regional Council – Napier, New Zealand
Information on the recruitment sources sustaining fish populations is integral to their effec- tive management, providing insights into early habitat requirements, population connectivity, and potential source-sink dynamics. However, the difficulty of tracking tiny larval and juvenile fish makes identifying recruitment sources particularly challenging for amphidromous species, which spend their larval period in a lake or the sea before migrating into streams as juveniles.
We used Sr87/Sr86 ratios of otoliths and water samples to attempt to determine the larval origins of large galaxiids in the lower Waikato, a catchment with many potential larval sources including the sea and a complex system of riverine lakes. To identify larval origins, we compared Sr87/Sr86 ratios in the larval zone of otoliths with water samples from all potential larval sources.
Nearly all fish examined had reared in lakes rather than the sea. While a few lakes had similar isotopic ratios which prevented definitive classification, discriminant function analysis classified the majority of fish to a larval rearing habitat with a high probability (>70%). Further, nearly all of these fish were classified to the nearest downstream lake from their location of capture, indicating limited dispersal between sub-populations. Subsequent larval trawls confirmed rela- tively high abundances of larvae rearing in those lakes identified as major sources of recruits.
These results demonstrate the potential for isotopic analyses of otoliths to be used in identifying sources of recruits to fish populations, and provide information crucial to the management and conservation of amphidromous fishes in the lower Waikato.
∗Speaker
Recruitment of Anguilla japonica glass eels in the Yangtze Estuary, China in relation to
environmental variables
Hongyi Guo ∗ 1, Xuguang Zhang 1, Ya Zhang 1, Wenqiao Tang† 1,2, Jiakun Song‡ 1
1 College of Fisheries and Life Science, Shanghai Ocean University – No.999, Huchenghuan Rd , Nanhui New City, Shanghai, P.R. China, China
2The Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Municipal Education Commission, Shanghai – No.999, Huchenghuan Rd , Nanhui New City, Shanghai, P.R. China, China
The recruitmentpattern of Anguilla japonica glass eels into the Yangtze estuary, China was studied during fivesuccessive migration seasons (2012–2016). The variation in daily catch was analyzed in relation to environmental factors that affect inshore migration. Two large migration waves of glass eels were observed in each recruitment season: one in the winter (January/February) and the other in the spring (March/April). A generalized additive model indicated that daily changes in glass eel catch were partially affected by local water temperature and tidal range. Water temperature seemed to have a threshold effect in winter, and there were optimal temperature ranges between 6-8◦C and approximately 10.5-12.0◦C associated with different recruitment waves to the Yangtze estuary. The influence of tides was complex, with an overall positive correlation. The annual glass eel catch fluctuated greatly, but generally did not show a significant downward trend. To achieve the sustainable use of glass eels, this paper proposes that relevant management and conservation activities should bereinforced.
Thyroid-hormone regulated metamorphosis:
a dynamic and plastic process allowing ecological and developmental coupling of life
history transitions
Vincent Laudet ∗† 1, Marc Besson 2, Guillaume Holzer 3, Natacha Roux 1, Pauline Salis 1, David Lecchini 2
1 OOB, UMR CNRS 7232 BIOM UPMC – oob – 1 avenue Pierre Fabre, 66650 Banyuls-sur-Mer, France
2 PSL Research University - EPHE-CNRS-UPVD USR3278 CRIOBE – BP1013 Papetoai, 98729 Moorea, French Polynesia
3 IGFL, UMR CNRS 5242, ENS Lyon – ´Ecole Normale Sup´erieure - Lyon – 46 All´ee d’Italie, 69364 Lyon Cedex 07, France
Vertebrate metamorphosis is a spectacular post-embryonic process exemplified by the trans- formation of a tadpole into a frog. This transition implies the appearance of new body parts (e.g. the limbs), the resorption of larval features(e.g. the tail) and the remodeling of many organs (e.g. the skin or the intestine). Metamorphosis has been well characterized in anuran amphibians, where thyroid hormone (TH) orchestrates the intricate and seemingly contradictory changes observed at the cellular and tissue levels. TH controls a complex hierarchical cascade of target genes via binding to specific receptors, TRa and TRb, which are ligand-activated transcription factors belonging to the nuclear receptor superfamily. Metamorphosis is in fact widespread throughout vertebrates, which exhibit an impressive diversity in this regard. How- ever, outside specific model systems or aquaculture species it is poorly characterized in fish and this is particularly true in coral reef fish. There are however many data suggesting that this is a critical period in the life history of these organism, intimately linked to larval recruitment a very important event in terms of ecology and conservation biology. In addition, variations of this key event (from paedomorphosis, the absence of metamorphosis, to direct development which actually corresponds to precocious metamorphosis) provides a unique opportunity to illustrate how the tinkering of the cascade controlling metamorphosis can lead to divergent life histories.
The data converge towards a model suggesting that post-embryonic remodeling governed by TH is a common feature in animals.
∗Speaker
†Corresponding author: vincent.laudet@obs-banyuls.fr
D1/ Biology, Ecology, Evolution and Conservation of Chondrichthyan
fishes
A Nursery Ground of Sicklefin Lemon Shark, Negaprion acutidens, at the Water of
Dongsha Island in Dongsha Atoll National Park, Taiwan
Chen Yu Yun ∗† 1, Wang Jeng Ping 2
1Department of Leisure Recreation Studies, Aletheia University – No.70-11, Beishiliao, Madou Dist., Tainan City 72147, Taiwan (R.O.C.), Taiwan
2 Department of Life Science, National Cheng Kung University (NCKU) – No.1, University Road, Tainan City 701, Taiwan (R.O.C.), Taiwan
Recent studies have indicated the survival of juvenile sharks is more important for population maintenance than the survival of adult stages. Dongsha island surrounded with seagrass beds, locate at the western opening of Dongsha Atoll. There has been documented adult female sicklefin lemon sharks come close to the near waters of Dongsha island every year, and even enter into the gape of the small lagoon during the high tide in late March and April. A few days after, several aggregations of juvenile sicklefin lemon sharks,Negaprion acutidens, would be seen and recorded along the waters of Dongsha island. 549 sicklefin lemon sharks, most were juveniles had been caught from September 2012 to April 2017. We found these sharks commonly inhabited seagrass beds along the coastline of Dongsha island, a behavior facilitating both observation and collection. 5 years visual surveys and trap collections revealed that juvenile sicklefin lemon sharks were abundant from May through September at water temperatures ranging from 24 to 30◦C.
Over 500 sampling yielded from 42–212 cm precaudal length (PCL), sex ratio of 0.83. Moving pattern and data from recaptured and acoustic tags showed nearshore migration here and mostly moved around the small lagoon, gape of the lagoon and the northern coast water of Dongsha island. Aggregations of juvenile lemon sharks documented might be the result of low-level water effect of the seagrass bed, which avoided the predation to the predator, meanwhile, provided the tidal area enhancing foraging opportunities as well as the protection from overfishing, which could be treated as a reserved area in sharks-depleted Southeast Asia waters. These findings indicate that nearshore waters of Dongsha island have been serve as one of the most valuable lemon shark nursery ground in South China Sea.
Keywords: nursery ground,Negaprion acutidens, Dongsha island.
∗Speaker
†Corresponding author: apodes@gmail.com
An Interactive Online Database for Extant Chondrichthyan Fishes
Gavin Naylor ∗ 1
1 Florida Museum of Natural History (FMNH) – 1659 Museum Road PO Box 117800 University of Florida Gainesville, FL 32611, United States
I will introduce a new website that provides access to information about the evolution, and biogeography of modern sharks, rays and chimaeras. The site contains scientific illustrations, distribution maps, estimated times of divergence and natural history pages for all currently described species. Interactive CT scans of skeletal elements are also available for representatives of several chondrichthyan families. The data are organized phylogenetically using an inference that is based on comparative genomic data. Queries can be conducted based on phylogeny, geography and depth of occurence..
Are we underestimating elasmobranch abundances on BRUVS by using traditional
metrics?
Samantha Sherman ∗ 1, Michelle Heupel 2,3, Andrew Chin 4, Colin Simpfendorfer 2
1James Cook University (JCU) – 1 James Cook Drive Townsville, Queensland 4810, Australia
2 Centre for Sustainable Tropical Fisheries and Aquaculture School of Earth and Environmental Sciences, James Cook University (JCU) – Townsville, Queensland, 4811, Australia
3 Australian Institute of Marine Science (AIMS Townsville) – Australian Institute of Marine Science PMB 3, Townsville MC Townsville 4810, Queensland, Australia, Australia
4Centre for Sustainable Tropical Fisheries and Aquaculture – College of Science and Engineering, James Cook University, 1 James Cook Drive, Townsville, QLD, 4811, Australia
Baited remote underwater video systems (BRUVS) are increasingly used to study aquatic fish communities, trends in biomass, and animal behaviour. The most commonly used metric to analyse BRUVS data is MaxN which refers to the maximum number of individuals observed in a single frame of a video. Here, we present a novel method for analysing BRUVS data that involves identifying and counting distinct individuals (MaxIND). Separate individuals of the oriental bluespotted maskray (Neotrygon orientalis) and the bluespotted fantail ray (Taeniura lymma), were identified on single BRUVS deployments by spot patterns, tail characteristics, and sex at three sites in Malaysian Borneo. We demonstrated that MaxIND gave abundances that were 2.4 and 1.1 times higher than MaxN for N. orientalis and T. lymma, respectively.
Results were consistent for each species between sites and both within and outside marine reserve boundaries. There were differences in abundance estimates from MaxN and MaxIND between species, meaning a single correction factor cannot be calculated for one species and applied to all species to better estimate true abundance. Identifying individuals, although time consuming, is a valuable method for analysing BRUVS footage as it provides improved accuracy in comparing species abundance.
∗Speaker
Baited remote underwater video system (BRUVS) survey of elasmobranch
abundance and distribution in the Arabian Gulf.
Rima Jabado∗ 1, Shamsa Al Hameli † 1, Edwin Grandcourt 1
1 Environment Agency Abu Dhabi (EAD) – PO Box:45553, Al Mamoura Building, Murour Road, Abu Dhabi, United Arab Emirates
Elasmobranch populations have declined worldwide raising conservation concerns for many species. Understanding the distribution of sharks and rays is therefore vital in developing conser- vation and management plans. Data on the relative abundance and diversity of elasmobranchs in the Arabian Gulf has been limited to fishery-dependent surveys undertaken at landing sites and fish markets. This available data therefore lacks details of distribution and habitat utilization of sharks and rays, which is crucial to inform policy. To determine the distribution and relative abundance of elasmobranchs across United Arab Emirates (UAE) Gulf waters, Baited Remote Underwater Video System (BRUVS) were deployed across a range of habitat types and depths.
BRUVS were deployed across randomly generated inshore and offshore locations (n=267) at depths between 2 and 25 m, from May-June 2015, March-June 2016, and September-December 2016. Preliminary data indicate that 12 species from 5 families were recorded with the dom- inant species being whiprays (Himantura spp.) and small carcharhinids in both summer and winter surveys. Preliminary Catch Per Unit Effort estimates suggests that despite the large area covered during the survey and extensive effort (over 700 hours of soak time), the abundance of elasmobranchs is significantly lower when compared to other regions of the world. This is the first comprehensive BRUVS survey of the relative abundance, diversity, and seasonal distribu- tion of elasmobranchs in the Gulf and results from this study will support the design of new conservation strategies for sharks and rays in the UAE.
Characterization, valuation and
conservation of the first nursery area of blacktip and hammerhead sharks in the
Eastern Atlantic Ocean
Catarina Frazao-Santos ∗ 1, Carina Vieira Da Silva 2, Rui Freitas 3, Rui Rosa† 1
1 Marine and Environmental Sciences Centre, University of Lisbon (MARE) – Laborat´orio Mar´ıtimo da Guia, Avenida Nossa Sra do Cabo 939, 2750-374 Cascais, Portugal
2 Centro de Estudos Florestais, Instituto Superior de Agronomia (ISA) – Instituto Superior de Agronomia, Tapada da Ajuda, 1349-017 Lisboa, Portugal
3 Cabo Verde Zoological Society (SZCV) – Caixa Postal 163, S˜ao Vicente, Rep´ublica de Cabo Verde, Cape Verde
Nursery areas, together with other key aggregation sites, are essential for effective conser- vation and management of sharks’ populations. Protecting shark nursery areas is also essential to ensure the provision of benefits to humans, as such areas support e.g. fisheries and ma- rine wildlife tourism activities. Here, we report the first potential shark nursery area in the Eastern Atlantic Ocean, namely in Sal Rei bay, Boa Vista Island (SR-BVI), Cape Verde. Pre- liminary data show that such area is greatly used by juvenile scalloped hammerhead sharks (Sphyrna lewini) and blacktip sharks (Carcharhinus limbatus) – species that are designated by the IUCN Red List as ”Endangered” and ”Near Threatened”, respectively. More specifically, we will present results from fourteen months of data collection on sharks’ catch per unit ef- fort (CPUE) and size/gender distribution, and also our approach to (1) estimate the economic value of the SR-BVI shark nursery area (i.e. discrete choice experiments, through on-site and off-site surveys to tourists and local populations), and (2) analyze the local marine governance system (i.e. institutional landscape, available management instruments). All this information will support the development of conservation measures and, subsequently, of a Shark Nursery Conservation Program – to be proposed to responsible entities. Although the SR-BVI shark nursery area is already partially covered by two of the 14 Natural Reserves located in Boa Vista Island, proposing a Shark Nursery Conservation Program is of the utmost importance because such reserves are not yet implemented (not having any management instruments in place), and do not encompass the entire SR-BVI area. Preliminary results regarding major challenges for sharks’ conservation in SR-BVI (including global change) will also be presented.
∗Speaker
†Corresponding author: rrosa@fc.ul.pt
Comparative behavioral and physiological response to longline capture in
elasmobranchs
Brendan Talwar ∗ 1, Edward Brooks 1, Ian Bouyoucos 1,2, Jacob Brownscombe 3, Steven Cooke 3, Corey Suski 4, John Mandelman 5
1 Cape Eleuthera Institute (CEI) – Shark Research and Conservation Program, Cape Eleuthera Institute, Rock Sound, The Bahamas, Bahamas
2 ARC Centre of Excellence for Coral Reef Studies (CoralCoE) – ARC Centre of Excellence for Coral Reef StudiesJames Cook University TownsvilleQueensland 4811 Australia, Australia
3 Department of Biology, Carleton University (Carleton University) – Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada, K1S5B6, Canada
4 University of Illinois (UofI) – Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, 61801, United States
5 Anderson Cabot Center for Ocean Life, New England Aquarium (NEAq) – 1 Central Wharf, Boston, MA 02110, United States
The behavioral response to longline capture in sharks is poorly understood although it may be tightly linked with the magnitude of the physiological stress response, and, ultimately, may contribute to stress-induced mortality. We employed accelerometers, video cameras, and hook timers to analyze the behavioral response of wild sharks to experimental longline capture across varied capture durations, temperatures, and depths. We also sought to relate behavioral re- sponses to the magnitude of physiological responses for captured animals. We found significant differences in fight intensity values across capture durations and species as well as between venti- lation modes in sharks, with RAM ventilators and blacktipsCarcharhinus limbatus in particular emerging as those demonstrating the most pronounced fighting behavior. We found no effect of fish size or capture temperature on fight intensity values. In addition, we found evidence of behavioral responses influencing the magnitude of physiological stress responses. Our results suggest that the behavioral and physiological response to longline capture is species-specific and highly variable and may be linked to distinct evolutionary traits, providing a frame of reference for vulnerability and risk assessments.
Conservation Status of Sharks, Rays, and Chimaeras in the Arabian Sea and Adjacent
Waters
Jabado Rima ∗ 1, Peter Kyne 2, Riley Pollom 3, Dave Ebert 4, Colin Simpfendorfer 5,6, Nicholas Dulvy 3
1Environment Agency Abu Dhabi (EAD) – Environment Agency – Abu Dhabi, P.O. Box 45553, Abu Dhabi, UAE, United Arab Emirates
2 Charles Darwin University – Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia
3IUCN Shark Specialist Group (IUCN SSG) – IUCN Species Survival Commission Shark Specialist Group and Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser
University, Burnaby, British Colombia V5A 1S6, Canada
4Pacific Shark Research Center – Pacific Shark Research Center, Moss Landing Marine Laboratories, Moss Landing, CA 95039, United States
5 Center for Sustainable Tropical Fisheries and Aquaculture (CSTFA) – School of Earth and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia
6James Cook University (JCU) – Centre for Sustainable Tropical Fisheries and Aquaculture and School of Earth and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
The Arabian Seas Region encompasses some of the most important chondrichthyan fish- ing and trading nations in the world. A regional IUCN Red List workshop was held in Abu Dhabi, United Arab Emirates, in February 2017 to assess the relative extinction risk of 153 chondrichthyan species occurring in the region. All assessments followed the IUCN Red List Criteria and Categories and their guidelines for application at the regional level. Overall re- sults indicate that the Arabian Seas Region has some of the most threatened chondrichthyan populations in the world. We conclude that at least half of species are threatened based on the observed threat level of assessed species combined with a modeled estimate of the number of Data Deficient species that are likely to be threatened. Of the 153 assessed species, 78 (50.9%) are classified as threatened: 14 (9.2%) are assessed as Critically Endangered (CR), 34 (22.2%) Endangered (EN), and 30 (19.6%) Vulnerable (VU). A further 27 species (17.6%) are categorized as Near Threatened (NT). Twenty-nine species (19%) are Data Deficient (DD) meaning that information is insufficient to assess their status. By assuming all or none of the DD species are threatened between 50.9% (if all Data Deficient (DD) species are not threatened) and 69.9%
(if all DD species are threatened). For sharks, 50.6% are threatened, while for batoids 52.7%
of extant species are threatened (range between 51.3% and 71%).The two species of chimaeras occuring in the region were not considered threatened. Chondrichthyan populations in the re- gion are showing significant declines and immediate actions are required to ensure the long-term sustainability of species. There is urgent need for concerted national and regional management measures to ensure extinctions are avoided and the sustainability of more productive species is secured.
∗Speaker
Direct evidence of contemporary sex-biased reproductive dispersal in threatened river
sharks.
Pierre Feutry ∗ 1, Oliver Berry 2, Peter Kyne 3, Richard Pillans 4, Richard Hillary 1, Peter Grewe 1, James Marthick 5, Rasanthi Gunasekera 1,
Floriaan Devloo-Delva 1, Nicholas Bax 1, Mark Bravington 1
1CSIRO – Oceans and Atmosphere, Castray Esplanade, Hobart 7000, Tasmania, Australia, Australia
2 CSIRO – Oceans and Atmosphere, PMB 5, Floreat 6014, Western Australia, Australia, Australia
3 Charles Darwin University – Research Institute for the Environment and Livelihoods, Charles Darwin University, Ellengowan Drive, Darwin 0909, Northern Territory, Australia, Australia
4CSIRO – Oceans and Atmosphere, 41 Boggo Road, Dutton Park 4102, Queensland, Australia, Australia
5University of Tasmania – Menzies Institute for Medical Research, University of Tasmania, 17 Liverpool Street, Hobart 7000, Tasmania, Australia, Australia
Measuring population connectivity is a critical task in conservation biology. While genetic markers can provide reliable long-term historical estimates of population connectivity, scientists are still limited in their ability to determine contemporary patterns of gene flow, the most prac- tical time frame for management. Also, contrasting results from mitochondrial nuclear DNA markers are often interpreted as evidence of sex-biased reproductive dispersal. However, differ- ences in genetic drift in mitochondrial and nuclear genes is an equally valid explanation. This approach combining mitochondrial and nuclear genes has been used in many chondrichthyes species and sex-biased reproductive dispersal is now suspected to be a common feature in this class, although it has never been formally demonstrated.
Here, we tackled these two issues by developing a new approach that only requires juvenile sampling at a single time period. To demonstrate the usefulness of our method, we used the Speartooth shark (Glyphis glyphis), a critically endangered species of river sharks found only in tropical northern Australia and southern Papua New Guinea.
Contemporary adult and juvenile shark movements was estimated with the spatial distribu- tion of kin pairs across and within three river systems. Over 200 full- and half-sibling pairs were identified. Full-sibling pairs were only captured within the same river suggesting that juveniles remain in the natal river for some time. Out of the 121 cross-cohort HS pairs, 103 were cap- tured within the same river system, indicating that in most cases at least one parent returned to reproduce in the same river system across breeding seasons. The remaining 18 cross-cohort