Simon Berrow

Marine mammals from northeast atlantic: relationship between their trophic status as determined by δ13C and δ15N measurements and their trace metal concentrations

The relationship between trophic position through delta13C and delta15N and trace metal concentrations (Zn, Cd, Cu and Hg) was investigated in the tissues of six marine mammal species from the Northeast Atlantic: striped dolphin Stenella coeruleoalba, common dolphin, Delphinus delphis, Atlantic white-sided dolphin Lagenorhynchus acutus, harbour porpoise Phocoena phocoena, white beaked-dolphin Lagenorhynchus albirostris, grey seal Halichoerus grypus stranded on French Channel and Irish coasts. White-beaked dolphins, harbour porpoises, white-sided dolphins, common and striped dolphins display the same relative and decreasing trophic position, as measured by delta15N values, along both the Irish and French channel coasts, reflecting conservative trophic habits between these two places. Hepatic and renal Cd concentrations were significantly correlated to muscle delta13C and delta15N values while Hg, Zn and Cu did not. These results suggest that Cd accumulation is partly linked to the diet while other factors such as age or body condition might explain Hg, Zn or Cu variability in marine mammals. Combined stable isotope and trace metal analyses appear to be useful tools for the study of marine mammal ecology.

PCB pollution continues to impact populations of orcas and other dolphins in European waters

Organochlorine (OC) pesticides and the more persistent polychlorinated biphenyls (PCBs) have well-established dose-dependent toxicities to birds, fish and mammals in experimental studies, but the actual impact of OC pollutants on European marine top predators remains unknown. Here we show that several cetacean species have very high mean blubber PCB concentrations likely to cause population declines and suppress population recovery. In a large pan-European meta-analysis of stranded (n = 929) or biopsied (n = 152) cetaceans, three out of four species:- striped dolphins (SDs), bottlenose dolphins (BNDs) and killer whales (KWs) had mean PCB levels that markedly exceeded all known marine mammal PCB toxicity thresholds. Some locations (e.g. western Mediterranean Sea, south-west Iberian Peninsula) are global PCB “hotspots” for marine mammals. Blubber PCB concentrations initially declined following a mid-1980s EU ban, but have since stabilised in UK harbour porpoises and SDs in the western Mediterranean Sea. Some small or declining populations of BNDs and KWs in the NE Atlantic were associated with low recruitment, consistent with PCB-induced reproductive toxicity. Despite regulations and mitigation measures to reduce PCB pollution, their biomagnification in marine food webs continues to cause severe impacts among cetacean top predators in European seas.

Organochlorine concentrations in resident bottlenose dolphins (Tursiops truncatus) in the Shannon estuary, Ireland

S.D. Berrow *, B. Mchugh , D. Glynn , E. Mcgovern , K.M. Parsons , R.W. Baird , S.K. Hooker e a Shannon Dolphin and Wildlife Foundation, Merchants Quay, Co. Clare, Kilrush, Ireland b Marine Institute, Abbotstown, Castleknock, Dublin 15, Ireland c Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen AB9 2TN, UK d Department of Biology, Dalhousie University, Halifax, NS, Canada B3M 4J1 e British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK

Habitat‐driven population structure of bottlenose dolphins, Tursiops truncatus, in the North‐East Atlantic

Despite no obvious barrier to gene flow, historical environmental processes and ecological specializations can lead to genetic differentiation in highly mobile animals. Ecotypes emerged in several large mammal species as a result of niche specializations and/or social organization. In the North‐West Atlantic, two distinct bottlenose dolphin (Tursiops truncatus) ecotypes (i.e. ‘coastal’ and ‘pelagic’) have been identified. Here, we investigated the genetic population structure of North‐East Atlantic (NEA) bottlenose dolphins on a large scale through the analysis of 381 biopsy‐sampled or stranded animals using 25 microsatellites and a 682‐bp portion of the mitochondrial control region. We shed light on the likely origin of stranded animals using a carcass drift prediction model. We showed, for the first time, that coastal and pelagic bottlenose dolphins were highly differentiated in the NEA. Finer‐scale population structure was found within the two groups. We suggest that distinct founding events followed by parallel adaptation may have occurred independently from a large Atlantic pelagic population in the two sides of the basin. Divergence could be maintained by philopatry possibly as a result of foraging specializations and social organization. As coastal environments are under increasing anthropogenic pressures, small and isolated populations might be at risk and require appropriate conservation policies to preserve their habitats. While genetics can be a powerful first step to delineate ecotypes in protected and difficult to access taxa, ecotype distinction should be further documented through diet studies and the examination of cranial skull features associated with feeding.

Accounting for the effects of lipids in stable isotope (δ13C and δ15N values) analysis of skin and blubber of balaenopterid whales

RATIONALE Stable isotope values (δ(13)C and δ(15)N) of darted skin and blubber biopsies can shed light on habitat use and diet of cetaceans, which are otherwise difficult to study. Non-dietary factors affect isotopic variability, chiefly the depletion of (13)C due to the presence of (12)C-rich lipids. The efficacy of post hoc lipid-correction models (normalization) must be tested. METHODS For tissues with high natural lipid content (e.g., whale skin and blubber), chemical lipid extraction or normalization is necessary. C:N ratios, δ(13)C values and δ(15)N values were determined for duplicate control and lipid-extracted skin and blubber of fin (Balaenoptera physalus), humpback (Megaptera novaeangliae) and minke whales (B. acutorostrata) by continuous-flow elemental analysis isotope ratio mass spectrometry (CF-EA-IRMS). Six different normalization models were tested to correct δ(13)C values for the presence of lipids. RESULTS Following lipid extraction, significant increases in δ(13)C values were observed for both tissues in the three species. Significant increases were also found for δ(15)N values in minke whale skin and fin whale blubber. In fin whale skin, the δ(15)N values decreased, with no change observed in humpback whale skin. Non-linear models generally out-performed linear models and the suitability of models varied by species and tissue, indicating the need for high model specificity, even among these closely related taxa. CONCLUSIONS Given the poor predictive power of the models to estimate lipid-free δ(13)C values, and the unpredictable changes in δ(15)N values due to lipid-extraction, we recommend against arithmetical normalization in accounting for lipid effects on δ(13)C values for balaenopterid skin or blubber samples. Rather, we recommend that duplicate analysis of lipid-extracted (δ(13)C values) and non-treated tissues (δ(15)N values) be used.

Effects of pingers on the behaviour of bottlenose dolphins

Trials were carried out in the Shannon estuary, Ireland, to test the effects of continuous (CPs) and responsive pingers (RPs) on bottlenose dolphin behaviour. In controlled trials, active and control pingers were deployed on fixed moorings, with T-PODs—acoustic monitoring devices to detect cetacean activity. In a separate trial, pingers were deployed from a moving boat which actively located dolphin groups in the estuary, and dolphin behaviour was recorded. In the static trials, overall detection rates of dolphin vocalizations on the T-POD were significantly lower in the presence of active CPs, but this was not the case for RPs. Mean inter-click interval values were longer for click trains produced in the presence of inactive RPs than for active RPs, active or inactive CPs. In boat-based trials, both active CPs and RPs appeared to affect bottlenose dolphin behaviour, whereby dolphins immediately left the area at speed and in a highly directional manner, involving frequent leaps.

Cetaceans in Irish waters: a review of recent research

To date, 24 cetacean species have been recorded in Irish waters. These are protected by a range of legislation, including the Whale Fisheries Act, the Wildlife Act and the EU Habitats Directive, which oblige Ireland to maintain cetacean populations and their habitat at a favourable conservation status. Policies aiming to maintain conservation objectives must be underpinned by scientifi c research. In this paper, we review historical and recent research on cetaceans in Irish waters (within the EEZ) to evaluate present knowledge and identify gaps in research. This information includes historical (pre-1976) records, targeted and incidental land, vessel and aerial based observations, acoustic surveys and monitoring and information from strandings. The habitat requirements of most cetacean species are not fully understood but some important habitats have been identifi ed. A number of threats to the welfare of cetaceans in Irish waters have also been identifi ed, including fi sheries interactions, pollution, climate change and disturbance. Future research required to fi ll gaps in knowledge highlighted by this manuscript is considered and discussed. Joanne O’Brien (corresponding author; email: joanne.obrien@gmit. ie); David McGrath, Department of Life Sciences, Galway– Mayo Institute of Technology, Dublin Road, Galway; Simon Berrow, Irish Whale and Dolphin Group, Merchants Quay, Kilrush, Co. Clare; Peter Evans, SeaWatch Foundation, 11 Jersey Road, Oxford 0X4 4RT, UK. Cite as follows: O’Brien, Joanne, Berrow, Simon, McGrath, David and Evans, Peter 2009 Cetaceans in Irish waters: A review of recent research. Biology and Environment: Proceedings of the Royal Irish Academy 109B, 63–88. DOI: 10.3318/ BIOE.2009.109.2.63. Received 13 December 2007. Accepted 29 October 2008. Published 30 July 2009. INTRODUCTION Irish coastal and offshore waters are some of the most important for cetaceans in Europe (Berrow 2001). Over the last two decades, there has been a rapid growth in our knowledge of the ecology of many cetacean species, due to an increase in research effort and the publication of literature. Numbers of cetacean-related publications have been consistently increasing since 1976 (Fig. 1). There has been an increase in national and international legal obligations for the protection of cetaceans and their habitats. Ireland has recently submitted the first conservation assessment of cetaceans under the EU Habitats Directive (NPWS 2008). For the 18 species (not including vagrants) that required an assessment, information on 12 of these species was reported as ‘unknown’, thus their conservation status could not be assessed. Ireland will be required to obtain sufficient information before the next reporting round of the Directive in 2013. In this paper, we review the current knowledge of cetacean ecology and research carried out to date in Irish waters. The overall aim of this review is to draw together all literature in a readily accessible format to identify information gaps and issues that should be addressed in the future, while contributing to the preparation of research and management plans. However, a detailed review and analysis of specific topics was beyond the scope of this paper. LEGISLATION There is a range of legislative instruments in Ireland aimed at protecting and managing cetaceans and their habitats. The first cetacean-related legislation enacted was the Whale Fisheries Act (1937) and associated Statutory Instruments, which required the licensing of all Irish-registered vessels engaged in whaling and banned the taking of (i) immature baleen whales (ii) female baleen whales accompanied by a calf, and (iii) all right whales. The conservation approach to whale and dolphin species was established with the Wildlife Act (1976) and Amendment (2000), which prohibited the hunting, injury, wilful interference and destruction of breeding places of cetaceans within the Exclusive Economic Zone (EEZ). The Government also issued guidelines to all boat operators in Ireland (Marine Notice no. 15, 2005) under a Statutory Instrument for correct procedures when encountering whales and dolphins, dictating inter alia that boats should not get closer than 100 metres and should maintain a speed of less than 7 knots. Ireland signed the Bern Convention on the Conservation of European Wildlife and Natural Habitats (1979), which offers protection to cetacean species. While this legally binding agreement did not extend the legal protection beyond that afforded by the Wildlife Act, it acted as a forerunner to more wide-ranging legislation. The protection of cetaceans was further extended Biology and Environment: Proceedings of the Royal Irish Academy, Vol. 109B, No. 2, 63–88 (2009).

Current Knowledge on the Distribution and Relative Abundance of Humpback Whales ( Megaptera novaeangliae ) off the Cape Verde Islands, Eastern North Atlantic

During the winter/spring months from 1990 to 2009, 13 cetacean surveys were conducted around the Cape Verde Islands off West Africa. The main target species was the humpback whale (Megaptera novaeangliae). Study periods varied from 14 to 90 d in duration. Study platforms included a 5-m inflatable boat, a 12-m catamaran, and/or 15-m sailing or motor vessels. Collectively, we obtained 88 individual humpback fluke photographs from this region. These fluke photographs have been compared to over 6,500 individual fluke photographs maintained in the North Atlantic Humpback Whale Catalogue. Based on photoidentification, humpbacks in the Cape Verde Islands have a relatively high interannual resight rate (> 22%) compared to other studied breeding locations in the West Indies. While this is partly due to increased probability of detection in a small population, this result nonetheless suggests strong site fidelity to this breeding ground. Three photo-identified individuals from the Cape Verde Islands had been previously photographed on high-latitude feeding grounds off Bear Island, Norway, and Iceland. One Cape Verdean humpback was resighted in the Azores, possibly en route to the northern feeding grounds. These findings are consistent with the belief that the Cape Verde Islands represent a breeding ground for northeastern Atlantic humpback whales. Tourism activities in the Cape Verde Islands are rapidly increasing. A balance is needed whereby conservation, whale watching guidelines, habitat preservation, and enforcement are fully enacted in order to provide protection to both this species and its habitat. In addition, further research is required to clarify the importance of this small population and its breeding ground.

Abundance Estimate of Bottlenose Dolphins (Tursiops truncatus) in the Lower River Shannon candidate Special Area of Conservation, Ireland

An abundance assessment of bottlenose dolphins (Tursiops truncatus) in the Lower River Shannon candidate Special Area of Conservation (cSAC) was undertaken between July and October 2010 using photo-identification. European Union Member States are obliged to designate SACs for bottlenose dolphins to protect important habitats. The Lower River Shannon is the only cSAC in Ireland for this species. A cumulative total of 273 bottlenose dolphins were photographed during the 12 transects, and from these a total of 116 individual animals were identified. They were categorized as follows: 71 with Severity Grade 1 marks, 21 with Severity Grade 2 marks, and 24 with Severity Grade 3 marks. There were 50 dolphins with permanent marks (Severity Grade 1) recorded on both sides of the dorsal fin, 64 on the left hand side only, and 57 on the right hand side only. There was an overlap, with some dolphins occurring in more than one category. Estimates of abundance were calculated using left side, right side, and both side identifications. The proportion of dolphins with re-identifiable marks (Severity Grade 1 only) ranged from 0.60 to 0.63. The estimated abundance of marked individuals was elevated depending on the estimated proportion of marked individuals in the population to give a final estimate of 107 ± 12, CV = 0.12 (95% CI = 83 to 131). Previous abundance estimates for bottlenose dolphins in the Lower River Shannon cSAC ranged from 114 in 2008 to 140 in 2006; the present estimate was within this range and also within the 95% Confidence Intervals for all surveys carried out to date. This suggests that, within the power of the survey technique, the population of bottlenose dolphins in the Lower River Shannon cSAC is relatively stable.

Social Structure Within the Bottlenose Dolphin (Tursiops truncatus) Population in the Shannon Estuary, Ireland

The Shannon Estuary is home to Ireland’s only known resident population of bottlenose dolphins (Tursiops truncatus) and is designated as a candidate Special Area of Conservation (cSAC) for this species. Proper conservation management of these dolphins requires an understanding of the social structure of this population. Four years of photoidentification data (2005 to 2009, excluding 2007) were used to construct sociograms that complement a cluster analysis of individually marked dolphins and their associates. The results found little evidence of social stability or group fidelity for this study’s dolphin population. Analysis of dolphins observed in consecutive years showed that the probability of group members encountering an individual dolphin in the second year did not depart from a random model. The social parameters for this resident population seem to be typical for this species. Bottlenose dolphins are found to exhibit a highly fluid, dynamic social structure within which individuals change their composition and associates regularly. These dolphins in the Shannon Estuary appear to live in a fission-fusion based society.