Characteristics of a manta ray Manta alfredi population off Maui, Hawaii, and implications for management

Late maturity, few offspring and a residential nature are typical characteristics of Manta alfredi that make this species vulnerable to localized anthropogenic threats. Improving its life history information is crucial for successful management. A total of 229 surveys was conducted from 2005 to 2009 at a manta ray aggregation site off Maui, Hawaii, to qualitatively and quantitatively describe the abundance, movements and temporal habits of this population. Photo-identifications revealed 290 unique individuals, but a discovery curve showed no asymptotic trend, indicating that the number of individuals using the area was much larger. Resightings and manta ray follows revealed that this population and a population off the Big Island may be independent, island-associated stocks. High resighting rates within and across years provided strong evidence of site fidelity. Findings were consistent with a population of manta rays moving into and out of the Maui aggregation area, with a varying portion of the total population temporarily resident at any given time. Males, accounting for 53% of all individuals, resided for shorter periods than females around the study area. Manta rays were usually absent at first light with numbers increasing throughout the day. More frequent mating trains were observed during the winter months. Shark predation was evident in 33% of individuals, and 10% had an amputated or non-functional cephalic fin. This small, demographically independent population appears vulnerable to the impacts from non-target fisheries, primarily from entanglement in fishing line, and could suffer from exploitation by commercial, unregulated ‘swim-with manta ray’ programs. Management on an island-area basis is recommended

Predictive modeling of spinner dolphin (Stenella longirostris) resting habitat in the main Hawaiian Islands

Predictive habitat models can provide critical information that is necessary in many conservation applications. Using Maximum Entropy modeling, we characterized habitat relationships and generated spatial predictions of spinner dolphin (Stenella longirostris) resting habitat in the main Hawaiian Islands. Spinner dolphins in Hawai'i exhibit predictable daily movements, using inshore bays as resting habitat during daylight hours and foraging in offshore waters at night. There are growing concerns regarding the effects of human activities on spinner dolphins resting in coastal areas. However, the environmental factors that define suitable resting habitat remain unclear and must be assessed and quantified in order to properly address interactions between humans and spinner dolphins. We used a series of dolphin sightings from recent surveys in the main Hawaiian Islands and a suite of environmental variables hypothesized as being important to resting habitat to model spinner dolphin resting habitat. The model performed well in predicting resting habitat and indicated that proximity to deep water foraging areas, depth, the proportion of bays with shallow depths, and rugosity were important predictors of spinner dolphin habitat. Predicted locations of suitable spinner dolphin resting habitat provided in this study indicate areas where future survey efforts should be focused and highlight potential areas of conflict with human activities. This study provides an example of a presence-only habitat model used to inform the management of a species for which patterns of habitat availability are poorly understood

Up close and personal: Recording humpback whale song at close ranges (10-50m)

Oceans Conference Record (IEEE)1472-OCNS

Research priorities to support effective manta and devil ray conservation

Manta and devil rays are filter-feeding elasmobranchs that are found circumglobally in tropical and subtropical waters. Although relatively understudied for most of the Twentieth century, public awareness and scientific research on these species has increased dramatically in recent years. Much of this attention has been in response to targeted fisheries, international trade in mobulid products, and a growing concern over the fate of exploited populations. Despite progress in mobulid research, major knowledge gaps still exist, hindering the development of effective management and conservation strategies. We assembled 30 leaders and emerging experts in the fields of mobulid biology, ecology, and conservation to identify pressing knowledge gaps that must be filled to facilitate improved science-based management of these vulnerable species. We highlight focal research topics in the subject areas of taxonomy and diversity, life history, reproduction and nursery areas, population trends, bycatch and fisheries, spatial dynamics and movements, foraging and diving, pollution and contaminants, and sub-lethal impacts. Mobulid rays remain a poorly studied group, and therefore our list of important knowledge gaps is extensive. However, we hope that this identification of high priority knowledge gaps will stimulate and focus future mobulid research