Responses of Australian sea lions,Neophoca cinerea,to anthropogenic activities in the Perth metropolitan area,Western Australia

1. Tourist‐based activities, partly due to their rapid increase, have raised concerns regarding the impacts of anthropogenic activity on marine fauna. Documented effects on pinnipeds in proximity to humans include changes in behaviour, site use and potentially higher aggression levels towards people. Effects vary considerably between populations and sites, thus requiring separate assessment of human impacts on activity and energy budgets.
2. Responses of the endangered Australian sea lion, Neophoca cinerea, to human visitation were recorded from November 2013 through April 2014. Exposure levels and response types to anthropogenic activities were assessed at two easily accessible locations with different management schemes, Seal (landing prohibited) and Carnac (landing permitted) islands, Western Australia. Exposure levels were measured as both stimulus type (i.e. ‘People’, ‘Paddlers’, ‘Small’, ‘Medium’, and ‘Large vessels’, ‘Tour vessels’, and ‘Jet skies’), and people (‘Direct’, ‘Attract’, ‘Interact’, ‘View’, ‘Incidental’, ‘Water’, ‘Low‐level’), and vessel activities (‘Interact’, ‘Approach/Follow’, ‘Anchor noise’, ‘Engine noise’, ‘Close to beach’, ‘Moderate/Fast travel’, ‘Slow travel’, ‘Transit’, ‘Drift/At anchor’, ‘Aircraft noise’).
3. Exposure levels varied significantly between the islands in numbers, stimuli type, duration and minimum approach distances. The instantaneous behaviours of ‘Lift head’, ‘Interact’ and ‘Sit’ were the most frequent responses. ‘Aggressive’ and ‘Retreat’ responses, the highest disturbance levels measured, occurred on Carnac approximately once per day, but rarely on Seal Island. ‘Aggressive’ behaviour towards ‘People’ was observed only on Carnac Island and elicited only by ‘People’. ‘People’, ‘Tour vessels’, and scenic ‘Aircrafts’ on both islands as well as ‘Jet skis’ on Carnac Island had the highest probability of triggering responses. Owing to their relatively high visitation at Seal Island, ‘Paddle powered vessels’, followed by ‘Tour vessels’ elicited the highest number of responses, compared with ‘People’, ‘Small’, and ‘Medium vessels’ at Carnac Island. The majority of responses occurred when any stimulus type was at short‐range (≤10 m), and ‘People’ ‘Viewing’ N. cinerea elicited most. Vessels triggered more responses at larger ranges than ‘People’.
4. To limit close‐range access to N. cinerea, one possibility is to close the beach at Carnac Island to human visitation and increase the minimum approach distance by vessels and ‘People’ by installing marker buoys at least 15 m from the shore.

© 2016 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd.     

Disturbance‐induced responses of VHF and satellite tagged harbour seals

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Monitoring long‐term changes in UK grey seal pup production

1. The population size of many species, particularly those in the aquatic environment, cannot be censused directly. Counts, during the breeding season, of one component of the population (e.g. breeding females) are often used as an index to allow investigation of trends. In species, such as grey seals (Halichoerus grypus), for which births are not tightly synchronous, single counts of pups represent an unknown proportion of the total number of pups born (pup production), and thus of breeding females (i.e. each pup born represents a breeding female).
2. Grey seals pup at large colonies around the coast of the UK. Information on their populations is required under national and international legislation.
3. In the UK, pup production has been monitored at some colonies since 1956. Currently, large colonies (~90% of UK pup production) are monitored either using ground (~10%; annually) or aerial surveys (~80%; annually until 2010, and thereafter biennially).
4. Here, the model used to estimate pup production at aerially surveyed colonies from 1987 to 2010 is described; structured pup counts from multiple surveys are combined with knowledge of life‐history parameters to model birth curves.
5. The resulting trends in pup production up to 2010 (aerially surveyed colonies) and 2016 (ground surveyed colonies) are examined.
6. In 2010, over 45,000 pups were estimated to be born in the UK. Pup production appeared to have reached an asymptote in the Inner Hebrides, Outer Hebrides and Orkney, whereas it is still increasing exponentially in the North Sea. Although density‐dependent processes acting at sea are likely to be responsible for these regional trends, we suggest that the substantial variation in trends within regions are likely caused by processes acting at the colony level. Some long‐established colonies, including Special Areas of Conservation, are exhibiting decreasing trends.
7. Special Areas of Conservation often serve as de facto monitoring sites and are the focus of management efforts. The observed temporal and spatial variability in patterns of colony growth rates highlight the potential risks of using such sites to develop wider management policies.

     

Operational interactions between South American sea lions and gillnet fishing in southern Brazil

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Behavioural responses of harbour seals to human‐induced disturbances

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Characterization of ocular gland morphology and tear composition of pinnipeds

Objective The importance of tear film integrity to ocular health in terrestrial mammals is well established, however, in marine mammals, the role of the tear film in protection of the ocular surface is not known. In an effort to better understand the function of tears in maintaining health of the marine mammal eye surface, we examined ocular glands of the California sea lion and began to characterize the biochemical nature of the tear film of pinnipeds. Procedures Glands dissected from California sea lion eyelids and adnexa were examined for gross morphology, sectioned for microscopic analysis, and stained with hematoxylin and eosin. The tear film was examined using interferometry. Tears were collected from humans and pinnipeds for the analysis of protein and carbohydrate content. Results The sea lion has sebaceous glands in the lid, but these glands are different in size and orientation compared with typical meibomian glands of terrestrial mammals. Two other accessory ocular glands located dorsotemporally and medially appeared to be identical in morphology, with tubulo‐acinar morphology. An outer lipid layer on the ocular surface of the sea lion was not detected using interferometry, consistent with the absence of typical meibomian glands. Similar to human tears, the tears of pinnipeds contain several proteins but the ratio of carbohydrate to protein was greater than that in human tears. Conclusions Our findings indicate that the ocular gland architecture and biochemical nature of the tear film of pinnipeds have evolved to adapt to the challenges of an aquatic environment.