scholarly journals Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

2021 ◽  
Vol 8 ◽  
Author(s):  
Brittany Finucci ◽  
Clinton A. J. Duffy ◽  
Tom Brough ◽  
Malcolm P. Francis ◽  
Marco Milardi ◽  
...  

Basking sharks (Cetorhinus maximus) were widely reported throughout New Zealand waters. Once commonly observed, and sometimes in large numbers, basking sharks are now infrequently reported. Basking shark observations are known to be highly variable across years, and their distribution and occurrence have been shown to be influenced by environmental predictors such as thermal fronts, chl-a concentration, and the abundance of prey (zooplankton). Little is known of basking sharks in the South Pacific and more information on distribution, habitat use, and migratory patterns is required to better understand the species’ regional ecology. Here, we used bootstrapped Habitat Suitability Models [HSM, ensembled from Boosted Regression Tree (BRT) and Random Forest (RF) models] to determine the drivers of basking shark distribution, predict habitat suitability and estimated uncertainty in the South Pacific for the first time. High−resolution environmental (1 km2 grid resolution) and biotic data, including inferred prey species, and all available basking shark records across New Zealand’s Exclusive Economic Zone (EEZ) were included in the ensemble HSMs. The most influential driver of modeled basking shark distribution was vertical flux of particulate organic matter at the seabed, which may indicate higher levels of primary production in the surface ocean and higher prey density in the mesopelagic zone and at the seafloor. The BRT and RF models had good predictive power (AUC and TSS > 0.7) and both models performed similarly with low variability in the model fit metrics. Areas of high basking shark habitat suitability included the east and west coasts of the South Island, Puysegur Ridge, and Auckland Island slope. The outputs produced here could be incorporated into future management framework for assessing threat and conservation needs (e.g., spatially explicit risk assessment) for this regionally protected species, as well as providing guidance for future research efforts (e.g., areas of interest for sampling).

1982 ◽  
Vol 10 (2) ◽  
pp. 221-226 ◽  
Author(s):  
Robert A. C. Stewart

Beliefs in overall trustworthiness, strength of will and complexity of others were investigated in: (a) 72 secondary students (mean age 17 years) from King George VI School in Solomon Islands, and (b) 120 students (Fijians, Indo-Fijians and other Pacific Islanders) at the University of the South Pacific in Suva, Fiji (mean age 23 years 5 months). The 36-item Wrightsman's Children's Philosophies of Human Nature Scale was used. Solomon Island subjects completed the inventory twice (to compare their attitudes to people inside and outside the wantok (pidgin term for immediate village, or group of people perceived as close.) it was shown that people outside the wantok are perceived as less to be trusted (p<0.01), and more complex (pK0.05). In a sex comparison it was shown that males were more likely than females to trust people outside the wantok and found them less complex (p<0.05. In analysis of the results from the University student sample, males were shown (pK0.01) to see people in general as having more strength of will and rationality than females. In an ethnic comparison it was shown (p<0.05) that Indo-Fijians had a higher belief in the trustworthiness of people than Fijians. This confirms previous research. The University students took the inventory under standard conditions. It is suggested that future research would find it fruitful to continue to explore the differences in attitudes, in this part of the world, toward people perceived as either “close” or “distant”.


2015 ◽  
Vol 465 ◽  
pp. 24-32 ◽  
Author(s):  
J. Lisa Hoogenboom ◽  
Sarah N.P. Wong ◽  
Robert A. Ronconi ◽  
Heather N. Koopman ◽  
Laurie D. Murison ◽  
...  

2011 ◽  
Vol 62 (11) ◽  
pp. 1327 ◽  
Author(s):  
Malcolm P. Francis ◽  
Mark A. Morrison ◽  
John Leathwick ◽  
Cameron Walsh

Estuarine fish habitats are vulnerable to human impacts and are poorly studied. We surveyed 69 of New Zealand’s 443 estuaries across 1500 km to: determine species composition of small fishes; model and predict their richness, occurrence and abundance; test marine classification schemes as a basis for Marine Protected Areas; and inform impact mitigation measures. Boosted regression tree models produced acceptable fits for richness and occurrence at estuary and site scales and abundance at the site scale. Richness was greatest in northern North Island; the best predictors were estuary area and area of intertidal habitat. Within estuaries, richness increased towards the head, as water clarity declined and the substratum became muddier. Air temperature, estuary and intertidal area, tidal range and freshwater and seawater influx were the best predictors of occurrence at the estuary scale; water temperature and salinity were important at the site scale. Biological classification schemes seldom improved model fits and have little predictive utility. Richness predictions were made for 380 estuaries and occurrence predictions for 16 species. These predictions inform resource managers about estuarine fishes within their jurisdiction, bypassing the need to undertake expensive field surveys. However, sampling of environmental predictors is still required to drive some models.


2020 ◽  
Author(s):  
Tyler E Schartel ◽  
Monica L Cooper ◽  
Aubrey May ◽  
Matthew P Daugherty

Abstract The spread and impact of invasive species in exotic ranges can be mitigated by increased understanding of pest invasion dynamics. Here, we used geospatial analyses and habitat suitability modeling to characterize the invasion of an important vineyard pest, vine mealybug (Planococcus ficus Signoret, Hemiptera: Pseudococcidae), using nearly 15,000 trapping records from throughout Napa County, California, between 2012 and 2017. Spatial autocorrelation among P. ficus detections was strongest at distances of ~250 m and detectable at regional scales (up to 40 km), estimates of the rate and directionality of spread were highly idiosyncratic, and P. ficus detection hotspots were spatiotemporally dynamic. Generalized linear model, boosted regression tree, and random forest modeling methods performed well in predicting habitat suitability for P. ficus. The most important predictors of P. ficus occurrence were a positive effect of precipitation in the driest month, and negative effects of elevation and distance to nearest winery. Our results indicate that 250-m quarantine and treatment zones around P. ficus detections are likely sufficient to encompass most local establishment and spread, and that implementing localized regulatory procedures may limit inadvertent P. ficus spread via anthropogenic pathways. Finally, surveys of P. ficus presence at &gt;300 vineyard sites validated that habitat suitability estimates were significantly and positively associated with P. ficus frequency of occurrence. Our findings indicate that habitat suitability predictions may offer a robust tool for identifying areas in the study region at risk to future P. ficus invasion and prioritizing locations for early detection and preventative management efforts.


2015 ◽  
Vol 61 (5) ◽  
pp. 811-826 ◽  
Author(s):  
Luis O. Lucifora ◽  
Santiago A. Barbini ◽  
Edgardo E. Di Giácomo ◽  
Juan A. Waessle ◽  
Daniel E. Figueroa

Abstract The distribution of the planktivorous basking shark Cetorhinus maximus is influenced by zooplankton abundance at small scales and temperature at medium scales in the North Atlantic. Here, we estimate the distribution of basking sharks on South Atlantic continental shelves, and the relative importance of chlorophyll concentration, as a proxy for zooplankton abundance, and temperature in determining habitat suitability for basking sharks at large scales. We used maximum entropy (MaxEnt) and maximum likelihood (MaxLike) species distribution modelling to test three hypotheses: the distribution of basking sharks is determined by (1) temperature, (2) chlorophyll concentration, or (3) both chlorophyll and temperature, while considering other factors, such as oxygen and salinity. Off South America, basking shark habitat included subtropical, temperate and cool-temperate waters between approximately 20°S and 55°S. Off Africa, basking shark habitat was limited to cool-temperate waters off Namibia and southern South Africa. MaxLike models had a better fit than MaxEnt models. The best model included minimum chlorophyll concentration, dissolved oxygen concentration, and sea surface temperature range, supporting hypothesis 3. However, of all variables included in the best model, minimum chlorophyll concentration had the highest influence on basking shark distribution. Unlike the North Atlantic distribution, the South Atlantic distribution of basking sharks includes subtropical and cool-temperate waters. This difference is explained by high minimum chlorophyll concentration off southern Brazil as compared to North Atlantic subtropical areas. Observations in other regions of the world support this conclusion. The highest habitat suitability for basking sharks is located close to nearshore areas that experience high anthropogenic impact.


2009 ◽  
Author(s):  
Anthony R. Paquin ◽  
Reinout E. de Vries ◽  
Raghuvar D. Pathak ◽  
Rafia Naz
Keyword(s):  

2019 ◽  
Vol 39 (1) ◽  
Author(s):  
Nick Towner ◽  
Semisi Taumoepeau

Abstract Tuvalu and Nauru are isolated developing island nations located in the South Pacific Ocean. In contrast to the established larger Pacific destinations such as Fiji and Tahiti, the tourism industries on both Tuvalu and Nauru are in their infancy. Tourism development in these remote island nations faces a myriad of challenges which include a lack of infrastructure, environmental susceptibility, economic vulnerability, difficulties with access and considerable distances from major tourist markets. This paper reviews tourism on Tuvalu and Nauru and evaluates their current situation regarding potential tourism development through workshops with relevant stakeholders, surveys and subsequent SWOT analysis. The results of the paper outlined a large number of challenges faced by Tuvalu and Nauru due to their geographic location but also highlighted that both Islands possess fascinating and unique features that have the potential to attract niche tourism markets. A key finding of this paper is that the tourism stimulus or potential attraction can also be the chief threat to the islands’ economic survival hence the two edges of the sword. Further research is required to assess the effect of the withdrawal of the Refugee Processing Centre on Nauru’s economy and to evaluate the impact of climate change on Tuvalu’s society and potential adaption strategies.


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