Working Group on Marine Mammal Ecology (WGMME)

159 pages.-- This work is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0)The Working Group on Marine Mammal Ecology met in 2022 to address five terms of reference. Under the first of these, ToR A, new information on cetacean and seal population abundance, distribution, population/stock structure, was reviewed, including information on vagrant ma-rine mammal species. This was done to ensure the recording of possible range changes in marine mammal species in the future. For cetaceans, an update is given for the different species, providing for a latest estimate for all species studies. In this report, particular attention is given to the updating of information from Canadian and US waters, and together with those countries, latest estimates for cetacean species are provided. For seals, latest monitoring results are given for harbour, grey and Baltic ringed seals. In addition, where possible, local long-term trends are illustrated for those species, based on earlier WGMME efforts to assemble these data into the WGMME seal database. For both spe-cies’ groups, a first account of vagrant species is providedN

Factors affecting the reliability and validity of behavioural datasets: Assessing the impact of observers' experience and native language on studies of wild animals

In animal behaviour studies, particularly those involving wild animals, the reliability and valid-ity of behavioural data collected by observers are not often examined. It is rarer still to see an assessment of the factors that may influence data collection. Variation in the reliability (the con-sistency of measurements) and the validity (the accuracy of measurements) by different observers may occur. This variability in data collection may have a significant impact on the accuracy of the results of a study. While the impact of observers' experience on reliability has been demonstrated in some studies, the influence of factors such as observers' native language is unknown. Herein, we used pre-recorded digital footage of migrating humpback whales (Megaptera novaeangliae) to examine the effects of observers' experience and native language on the reliability and validity of their data collection. We found that neither factor (experience nor native language) had a signifi-cant effect overall. However, within the dataset, specific behavioural types were found to be more accurately and consistently recorded than others. The results of this study help identify behav-ioural types that may require redefinition in the ethogram as well as those that were not reliably recorded and that should be excluded from further analysis. This information enables future research to optimise the reliability and validity of behav-ioural data collected at the site and to help identify robust variables for inclusion in data analysis

The effect of close approaches for tagging activities by small research vessels on the behavior of humpback whales (Megaptera novaeangliae)

Small research vessels are often used as platforms for tagging activities to collect behavioral data on cetaceans and they have the potential to disturb that group or individual. If this disturbance is ignored, results and conclusions produced by that study could be inaccurate. Here land-based behavioral data of migrating humpback whales (Megaptera novaeangliae) (n = 29) were used to determine the effect of close approaches for tagging by research vessels on their diving, movement and surface behaviors. Groups of whales were tagged, using digital recording tags, by small research vessels, as part of a behavioral response study. In groups that were approached for tagging, temporary changes in movement behaviors during close approaches were found, with subsequent recovery to “pre-approach” levels. In female-calf groups more long-term changes in travel speed were found. Results suggest that, although close approaches for tagging by small vessels may cause behavioral changes in humpback whales, this change may be small and temporary. However, in female-calf groups, the behavioral change may be greater and longer lasting. This study shows that when using small vessels for behavioral research, disturbance, and recovery should be measured to ensure integrity of data used for other analyses

Potential energy gain by whales outside of the Antarctic: prey preferences and consumption rates of migrating humpback whales (Megaptera novaeangliae)

The humpback whale (Megaptera novaeangliae) makes annual migrations from Antarctic feeding grounds to tropical breeding grounds. The extent to which it feeds during migration is unknown, but thought to be very low. Whether an animal feeds during migration is likely dependent on prey availability and on the ease with which it can capture the available prey. This study used digital tags (DTAGs) and concurrent prey sampling to measure how changes in the depth and type of prey influenced the lunge feeding rates and the amount of energy consumed by migrating humpback whales. Whales targeting krill lunged at significantly higher rates than whales targeting fish; however, the depth of the prey did not influence lunge rate. The observed lunge rates when feeding on krill, to the best of our knowledge, are higher than any previously reported rates of whales feeding. Estimates of the energetic content of the prey ingested revealed that whales may consume between 1.2 and 3.4 times their daily energy requirements per day while feeding on krill during migration, but less when feeding on fish. This suggests that whales may begin to restock energy supplies prior to reaching the Antarctic. Determining how often this high rate of energy intake occurs along the migratory route will assist with understanding the contribution of migratory energy intake to annual energy budgets

Evidence for the functions of surface-active behaviors in humpback whales (Megaptera novaeangliae)

As part of their social sound repertoire, migrating humpback whales (Megaptera novaeangliae) perform a large variety of surface-active behaviors, such as breaching and repetitive slapping of the pectoral fins and tail flukes; however, little is known about what factors influence these behaviors and what their functions might be. We investigated the potential functions of surface-active behaviors in humpback whale groups by examining the social and environmental contexts in which they occurred. Focal observations on 94 different groups of whales were collected in conjunction with continuous acoustic monitoring, and data on the social and environmental context of each group. We propose that breaching may play a role in communication between distant groups as the probability of observing this behavior decreased significantly when the nearest whale group was within 4,000 m compared to beyond 4,000 m. Involvement in group interactions, such as the splitting of a group or a group joining with other whales, was an important factor in predicting the occurrence of pectoral, fluke, and peduncle slapping, and we suggest that they play a role in close-range or within-group communication. This study highlights the potentially important and diverse roles of surface-active behaviors in the communication of migrating humpback whales

Workshop on the production of swept-area estimates for all hauls in DATRAS for biodiversity assessments (WKSAE-DATRAS). ICES Scientific Reports, 3:74.

The workshop on the production of swept-area estimates for all hauls in DATRAS for biodiver-sity assessments (WKSAE-DATRAS) considered three groups of surveys for which data are sub-mitted to the Database of Trawl Surveys (DATRAS): various Beam Trawl Surveys, the Northeast Atlantic International Bottom Trawl Survey (Northeast Atlantic IBTS), and the North Sea Inter-national Bottom Trawl Survey (North Sea IBTS). All countries contributing to the above-mentioned surveys were represented by at least one par-ticipant during the workshop, apart from the Netherlands and Norway. The main objectives of the workshop were to establish tow-by-tow swept-area estimates for time-series as far back in time as possible, compare different approaches for the estimates of missing observations, and harmonize the resulting dataseries for biodiversity assessments. For all of the surveys considered, problems with data quality were detected. This included the Beam Trawl Surveys but was most pronounced for the North Sea IBTS. Outliers and potential erroneous data were listed for reporting back to the respective national institutes. In particular, missing observations or algorithms affected wing spread-based swept-area, which is needed in several applications. This workshop compared the Marine Scotland Science-MSS/OSPAR approach, which includes a data quality check for the information needed for the calculation of swept-area, and the DATRAS approach, which depends solely on correctly reported data from the national institutes. Larger data gaps were identified, in particular for several years of the North Sea IBTS. For those surveys, it is proposed that the best possible way forward at this moment is to use estimates based on the MSS/OSPAR approach. However, if dubious records (i.e. extreme outliers) were identified by the MSS/OSPAR and no other information was available, values (e.g. speed over ground or the depth at which a change from short to long sweeps should have happened) were taken from the manual. However, expe-rience has shown that the survey manuals are not followed in all instances, and so persistent country-specific and survey-specific deviations may occur. The national institutes are encouraged to check, correct, and fill in missing survey data through re-submissions to DATRAS. It is recommended that DATRAS data quality control on data sub-mission is extended for the information needed for the calculation of swept-area (e.g. distance, depth, door spread, and wing spread) and that this is done in close cooperation between the ICES Data Centre and the respective ICES survey working groups, WGBEAM (Working Group on Beam Trawl Surveys) and IBTSWG (International Bottom Trawl Survey Working Group)

Workshop on the production of abundance estimates for sensitive species (WKABSENS). ICES Scientific Reports, 3:96.

The Workshop on the production of annual estimates of abundance of sensitive species (WKABSENS) met to define sensitive species, collate ICES assessments of abundance where these are available, and estimate indices of their abundance per swept-area where not, for the OSPAR area. The analyses identified 140 potentially sensitive species or species complexes, among which 10 are diadromous and three are coastal, 20 have uncertain species ID and nine were identified as sensitive in only one of the sources examined. Among the sensitive species and species complexes, there was sufficient data to provide abundance indices for 50 species, of which 16 had existing stock assessments whereas the workshop derived abundance estimates for the remaining 34 species from survey data. Three statistical modelling approaches (binomial, General Additive Models (GAMs) and VAST) and were explored and the final abundance indices were calculated using GAMs. The species were divided into stocks before estimating abundance indices where these could be identified from the spatial distribution of the species in the survey. The group considered that a similar analysis using data from additional surveys, commercial indices or data from bycatch observers can potentially provide improved abundance estimates for species with variable or low catchability, such as deep-water and pelagic species