scholarly journals Estimating population size, structure, and residency time for whale sharks Rhincodon typus through collaborative photo-identification

2009 ◽  
Vol 7 ◽  
pp. 39-53 ◽  
Author(s):  
J Holmberg ◽  
B Norman ◽  
Z Arzoumanian
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Rhincodon Typus ◽  
Photo Identification ◽  
Population Size Structure ◽  
Whale Sharks ◽  
Residency Time

Population size structure and sex ratios in some woodlice (Crustacea: Oniscidae) from southern Africa

1994 ◽  
Vol 10 (2) ◽  
pp. 261-271 ◽  
Author(s):  
J. M. Dangerfield ◽  
S. R. Telford
Keyword(s):  
Population Size ◽  
Southern Africa ◽  
Life Histories ◽  
Mating Systems ◽  
Size Structure ◽  
Sex Ratios ◽  
Interspecific Variation ◽  
Sexual Competition ◽  
Population Size Structure ◽  
Adult Sex Ratio

ABSTRACTThe population size structure and adult sex ratio were recorded for four indigenous and one introduced species of terrestrial isopod from southern Africa. Interspecific variation was considerable with either discrete or continuous distributions indicative of the production of separate cohorts or continuous recruitment. Intraspecific variation was also considerable particularly in species such as Aphiloscia vilis which can be found in diverse habitats. Sex ratios were consistently female biased, a result consistent with observations made on temperate species. These observations, and a consideration of sexual dimorphism based on body mass, suggest that phenotypic plasticity may be an important tactic in the life histories of tropical woodlice and that in some populations the potential exists for strong sexual competition and complex mating systems.

scholarly journals Sizing and scarring of whale shark (Rhincodon typus Smith, 1828) in the Cenderawasih Bay National Park

2021 ◽  
Vol 21 (3) ◽  
pp. 199-213
Author(s):  
Yusup A Jentewo ◽  
Roni Bawole ◽  
Tresia S Tururaja ◽  
Mudjirahayu Mudjirahayu ◽  
Zeth Parinding ◽  
...  
Keyword(s):  
National Park ◽  
The Body ◽  
Whale Shark ◽  
Gill Slit ◽  
Rhincodon Typus ◽  
Photo Identification ◽  
Dorsal Fin ◽  
Total Length ◽  
Whale Sharks ◽  
Photo Collection

This study aims to determine the total length and scar condition of the body of whale sharks (Rhincodon typus) in Cendrawasih Bay National Park (TNTC), Papua-Indonesia. Photo-identification was used to identify individuals of the whale shark R. typus based on spot patterns behind the last gill slit of each individual. Photo-identification was also used to determine the scar of the whale shark. The total length of whale sharks were estimated based on the length of a snorkeller (assumed to be 1.6 m) swimming alongside the whale shark. We identified 21 individuals of R. typus. Of these 21 individuals, 14 were new sightings and seven were re-sightings that have been recorded in the previous photo collection database. R. typus ranged in size from 2 to 5 m total length (average 3.78 m, ±0,86, N= 21). Based on their size, all individuals of whale shark were categorized as juvenile. 52% of R. typus identified had scars and 38 % were not and 10% were unknown. The majority of whale sharks had amputation (12 individuals) and abrasion (7 individuals) scars. Scars occurred most often on the caudal fin and dorsal fin, five and four individuals respectively. This information is useful for understanding potential threats and designing better management programmes for R. typus conservation in TNTC.

scholarly journals Regional connectivity of whale sharks demonstrated using photo-identification – Western Atlantic, 1999 - 2013

2013 ◽  
Author(s):  
Jennifer McKinney ◽  
Eric R Hoffmayer ◽  
Jason Holmberg ◽  
Rachel Graham ◽  
Rafael de la Parra ◽  
...  
Keyword(s):  
Population Size ◽  
Transition Probabilities ◽  
Regional Cooperation ◽  
Individual Heterogeneity ◽  
Whale Shark ◽  
Western Atlantic ◽  
Entire Study ◽  
Photo Identification ◽  
Initial Identification ◽  
Whale Sharks

Background: Although whale sharks (Rhincodon typus) occur circum-globally, most studies focus on feeding aggregations in small regional areas. Photo identification is a proven tool in assessing population size and structure. While population estimates have been obtained for individual aggregation sites, there has been a lack of broader estimates despite known movement. The aim of this work is to demonstrate connectivity throughout the Gulf of Mexico (GOM) and Caribbean, and provide the first regional population estimate. Methods: Photographs submitted to the ECOCEAN Whale Shark Photo-ID Library Sightings were used to identify individual sharks using techniques described in Holmberg et al. (2009). Sightings data were used to assess the lagged identification rate (LIR) in order to investigate residency, regional mixing, population size, and transition probabilities using modules within SOCPROG 2.4. Results: Identifications from 1998 – 2013, were obtained from Belize (n =132), Mexico (n=3642), Honduras (n = 360), and the USA (n=147). Fifty-four individual sharks were seen in more than one country and used for analysis. For the entire study area, LIR decreased rapidly between one and 64-127 (mean 94.4) days then slightly increased between 256-511 (mean 381.2) days, suggesting a near-annual resighting periodicity. Estimates of mean population size from the best-fitting model were 1897.39 ± 414.30 S.E. (95% C.I. 1191.77 – 2784.03). Evidence suggests individual heterogeneity in movement patterns. Resightings were most likely to occur in the country where initial identification occurred, with the exception of Belize. The highest site fidelity was in Mexico, followed by USA. Conclusions: This study demonstrated individual heterogeneity, fidelity to initial identification site and regional linkages. These data suggest that national and regional cooperation is required for successful whale shark management in the West Atlantic.

Growth, reproduction, and population structure in four alpine lichens during 240 years of primary colonization

2004 ◽  
Vol 82 (9) ◽  
pp. 1356-1362 ◽  
Author(s):  
Geir Hestmark ◽  
Olav Skogesal ◽  
Øystein Skullerud
Keyword(s):  
Population Size ◽  
Life Histories ◽  
Size Structure ◽  
Growth Period ◽  
Maximum Size ◽  
Strongly Correlated ◽  
Interspecific Differences ◽  
Population Size Structure ◽  
The Relationship ◽  
Plant Life Histories

The increase in thallus diameter and apothecium production, and the population size structure of the saxicolous lichens Umbilicaria cylindrica (L.) Del., Umbilicaria hyperborea (Ach.) Hoffm., Umbilicaria proboscidea (L.) Schrad, and Umbilicaria torrefacta (Lightf.) Schrad, were measured in a chronosequence of 240 years in a glacier foreland in the alpine Jotunheimen National Park in Norway. All four species exhibited a pattern of fast growth in the early decades of their life history, followed by a rapid decrease in growth, slowly approaching a maximum body size. There were clear interspecific differences in initial estimated growth rate, growth period, and maximum size. In all species, apothecium production is strongly correlated with thallus size, but in U. hyperborea the relationship approximates an exponential function, while in the other species the trend is more linear. In U. proboscidea, the slowest to mature, a fairly high proportion of sterile individuals also occur in the higher size classes. There was no observed trade off between growth and reproduction. Quite the contrary: the species that grow faster also start to reproduce abundantly and early. The relatively slow growth and reproductive maturation of the species implies that a population of 40- to 50-year-old individual thalli is still a population consisting mainly of immigrants. The population size structure of all four species remains strongly skewed during the entire chronosequence, with a predominance of small thalli.Key words: plant life histories, lichen growth rates, size structure, Umbilicaria.

Efficacy of population size structure as a bioassessment tool in freshwaters

2013 ◽  
Vol 34 ◽  
pp. 571-579 ◽  
Author(s):  
Christina A. Murphy ◽  
Frederic Casals ◽  
Carolina Solà ◽  
Nuno Caiola ◽  
Adolf de Sostoa ◽  
...  
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Population Size Structure
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