Abundance and population structure of queen conch inside and outside a marine protected area: repeat surveys show significant declines

Animal forests promote marine habitats morphological complexity and functioning. The red gorgonian, Paramuricea clavata, is a key structuring species of the Mediterranean coralligenous habitat and an indicator species of climate effects on habitat functioning. P. clavata metrics such as population structure, morphology and biomass inform on the overall health of coralligenous habitats, but the estimation of these metrics is time and cost consuming, and often requires destructive sampling. As a consequence, the implementation of long-term and wide-area monitoring programmes is limited. This study proposes a novel and transferable Structure from Motion (SfM) based method for the estimation of gorgonian population structure (i.e., maximal height, density, abundance), morphometries (i.e., maximal width, fan surface) and biomass (i.e., coenenchymal Dry Weight, Ash Free Dried Weight). The method includes the estimation of a novel metric (3D canopy surface) describing the gorgonian forest as a mosaic of planes generated by fitting multiple 5 cm × 5 cm facets to a SfM generated point cloud. The performance of the method is assessed for two different cameras (GoPro Hero4 and Sony NEX7). Results showed that for highly dense populations (17 colonies/m2), the SfM-method had lower accuracies in estimating the gorgonians density for both cameras (60% to 89%) than for medium to low density populations (14 and 7 colonies/m2) (71% to 100%). Results for the validation of the method showed that the correlation between ground truth and SfM estimates for maximal height, maximal width and fan surface were between R2 = 0.63 and R2 = 0.9, and R2 = 0.99 for coenenchymal surface estimation. The methodological approach was used to estimate the biomass of the gorgonian population within the study area and across the coralligenous habitat between −25 to −40 m depth in the Portofino Marine Protected Area. For that purpose, the coenenchymal surface of sampled colonies was obtained and used for the calculations. Results showed biomass values of dry weight and ash free dry weight of 220 g and 32 g for the studied area and to 365 kg and 55 Kg for the coralligenous habitat in the Marine Protected Area. This study highlighted the feasibility of the methodology for the quantification of P. clavata metrics as well as the potential of the SfM-method to improve current predictions of the status of the coralligenous habitat in the Mediterranean sea and overall management of threatened ecosystems.

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Conservation of coastal stingrays: seasonal abundance and population structure of the short-tailed stingray Dasyatis brevicaudata at a Marine Protected Area

ICES Journal of Marine Science ◽

10.1093/icesjms/fss120 ◽

2012 ◽

Vol 69 (8) ◽

pp. 1427-1435 ◽

Cited By ~ 13

Author(s):

A. Le Port ◽

S. Lavery ◽

J. C. Montgomery

Keyword(s):

Population Structure ◽

Life History ◽

Protected Area ◽

Marine Protected Area ◽

Marine Reserve ◽

Conservation Strategy ◽

Seasonal Abundance ◽

Management Tools ◽

Life History Stages ◽

Effective Conservation

Abstract Le Port, A., Lavery, S., and Montgomery, J. C. 2012. Conservation of coastal stingrays: seasonal abundance and population structure of the short-tailed stingray Dasyatis brevicaudata at a Marine Protected Area. – ICES Journal of Marine Science, 69: . Elasmobranch (shark, ray, and skate) populations around the world are in decline, and effective conservation measures are urgently needed. Marine Protected Areas (MPA) placed in locations important for key life-history stages may form part of an effective conservation strategy. In this context, we examined the seasonal abundance and population structure of the short-tailed stingray (Dasyatis brevicaudata) at an offshore MPA in northeastern New Zealand, and the reported use of this location as a mating ground. Diver surveys were conducted from 2004 to 2007 at the Poor Knights Islands Marine Reserve (PKIMR). During this time, we observed: (i) a substantial increase in adult and subadult numbers, particularly females during the suggested breeding season, and a corresponding increase in females bearing fresh mating scars; and (ii) large numbers of smaller (probably immature) D. brevicaudata individuals of both sexes from spring to autumn. These results suggest that the PKIMR acts as both a mating aggregation location and a nursery for this species. We suggest that for coastal stingrays such as D. brevicaudata, small MPAs may be effective at protecting key life-history stages, but that as movements outside of reserve boundaries also occur, additional management tools may also be necessary.

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Reproduction and population structure of Octopus mimus fished in a Marine Protected Area of Ecuador

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315417000613 ◽

2017 ◽

Vol 98 (6) ◽

pp. 1383-1389 ◽

Cited By ~ 3

Author(s):

Unai Markaida ◽

Luis Flores ◽

Evelyn Arias ◽

Elba Mora

Keyword(s):

Body Weight ◽

Population Structure ◽

Protected Area ◽

Marine Protected Area ◽

Mantle Length ◽

Eastern Pacific ◽

Small Scale ◽

Spawning Period ◽

Sampling Programme ◽

Santa Elena

Octopus mimus is the main octopus targeted by the small-scale fishery in the Eastern Pacific. Commercial catches of octopus from the Reserva de Producción Faunística Marino-Costera Puntilla de Santa Elena (REMACOPSE) Marine Protected Area in Ecuador were sampled from July to December 2013 in order to describe the reproduction and population structure of this octopus. The 4171 sampled octopuses ranged from 56 to 250 mm in mantle length (ML) and 45 to 3178 g in body weight (BW). Mean octopus weight did not change monthly. Males were mostly mature while the majority of females were immature. Presence of some mature and a few spent females in all months sampled suggests that the population shows an extended spawning period. No spawning peak could be properly defined. Sex ratios did not significantly shift from the expected 1:1 in most samples. Females mature at a larger size (1234 g, BW; 165 mm, ML) than males (487 g BW; 114 mm ML). We recommend considering a minimum legal size of 1200 g BW. A year-long sampling programme for O. mimus should also be completed in order to detect any spawning peak.

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REPRODUCTIVE DYNAMICS AND POPULATION STRUCTURE OF OCTOPUS INSULARIS FROM THE VERACRUZ REEF SYSTEM MARINE PROTECTED AREA, MEXICO

Fisheries Research ◽

10.1016/j.fishres.2019.105385 ◽

2020 ◽

Vol 221 ◽

pp. 105385 ◽

Cited By ~ 1

Author(s):

Roberto González-Gómez ◽

César Meiners-Mandujano ◽

Piedad S. Morillo-Velarde ◽

Lourdes Jiménez-Badillo ◽

Unai Markaida

Keyword(s):

Population Structure ◽

Protected Area ◽

Marine Protected Area ◽

Reef System

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Zonation and reef size significantly influence fish population structure in an established marine protected area, iSimangaliso Wetland Park, South Africa

Ocean & Coastal Management ◽

10.1016/j.ocecoaman.2019.105040 ◽

2020 ◽

Vol 185 ◽

pp. 105040 ◽

Cited By ~ 1

Author(s):

Vivienne Dames ◽

Anthony Bernard ◽

Camilla Floros ◽

Bruce Mann ◽

Conrad Speed ◽

...

Keyword(s):

South Africa ◽

Population Structure ◽

Protected Area ◽

Marine Protected Area ◽

Fish Population ◽

Fish Population Structure

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Growth parameters and density variation of a queen conch, Strombus gigas (Neotaenioglossa: Strombidae), population from Xel-Ha park, a marine protected area

10.31230/osf.io/rs9jd ◽

2018 ◽

Author(s):

Erick R. Baqueiro-Cardenas

Keyword(s):

Protected Area ◽

Marine Protected Area ◽

Growth Parameters ◽

Density Variation ◽

Growth Equation ◽

Von Bertalanffy ◽

Population Number ◽

Strombus Gigas ◽

Queen Conch ◽

Number Variation

This contribution used mark-recapture data to estimate the von Bertalanffy equation parameters and population number variation within a non harvest population from a protected area, to clarify the biometric parameters that better suit for the whole population, or for the juvenile and adult fractions. Conchs from XelHa Park were monthly sampled from November 2001 to August 2005. Every conch found was measured and marked with a numbered tag that identified month and locality; and monthly abundance was estimated with Jolly’s method. Length, lip thickness and weight increments were used to estimate the von Bertalanffy growth equation parameters with Appeldoorn’s subroutine of FISAT program. The population numbervaried through the study, with a minimum of 49 in April 2003 and maximum of 9 848 during June 2005. Conchs make only temporary use of Xel-Ha cove. Shell length gavethe best fit for the juvenile fraction: L∞=251, K=0.3, C=0.8 Wp=0.3; and lip thickness for adults: L∞=47.78, K=0.17, C=0.1, Wp=0.86, while, the whole population was better represented by weight: L∞=3850, K=0.36, C=0.8, Wp=0.3. A maximum age of 19 years was estimated from the population. Natural mortality was 0.49/year for juveniles and 0.29/year for adults. There were two pulses of recruitment: fall-winter and summer. It is concluded that population studies from length frequency data, should be analyzed independently in two groups, shell for the juvenile fraction and lip thickness for the adult fraction, or if it is not possible to analyze the population fractions separately,weight should be used to avoid miss calculation of the age structure.

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