Biology, ecology and fishery of sharks and their relatives Research Papers (original) (raw)

En el segundo capítulo se analiza información pesquera de los tiburones incluidos en la cites, de importancia económica en las distintas pesquerías y regiones de México, en particular de los tiburones martillo, ya que en el aps realizado previamente se detectó que son los de mayor riesgo ecológico. El análisis pesquero se realiza con base en información obtenida durante los últimos años en investigaciones desarrolladas por los programas de investigación del Instituto Nacional de Pesca (inapesca), directamente en las pesquerías de las distintas regiones. Se presenta por primera vez información del Programa de Observadores a bordo de las embarcaciones tiburoneras de mediana altura del Pacífico Noroeste, que inició en 2006 y que ha generado valiosa información sobre la distribución, estacionalidad y dinámica de las capturas de estas especies y de su biología.

The blue shark Prionace glauca (Linnaeus) is the most
abundant species in the artisanal shark fishery off the western
coast of Baja California Sur, Mexico. However, there is
no biological information on the reproduction of blue
sharks in this area. A total of 1033 sharks (631 males and
402 females) were sampled from August 2000 to March
2003. The sex ratio was 0.63F:1M. The size at maturity
(L50) for males was 184 cm total length (TL) and 196 cm
TL for females. The litter size ranged from 9 to 64, with a
mode of 33 embryos. Ovulation, fertilization, presence of
uterine eggs and the smallest embryos were observed in
August and September; whereas complete embryos were
recorded in May and July, with a gestation period of 9 to
11 months. We found compound spermatozeugmata in
the seminal vesicle of mature males and sperm in the oviducal
glands of females in different maturity stages, which
indicate long-term sperm storage. We confirm that the
main portion of the shark fishery in Baja California Sur is
supported by juvenile sharks.

- by Maribel Carrera Fernandez and +1
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- Biology, ecology and fishery of sharks and their relatives

Durante el periodo de febrero a julio de 2010 se evaluó la captura incidental de tiburones asociada a la actividad pesquera del sector de Bocas de Ceniza, Caribe colombiano. Para esto fue necesario realizar una caracterización de la actividad pesquera en el sector y un seguimiento de las capturas desembarcadas. Se observaron dos tipos de unidades económicas de pesca, las mayores (UEP), las cuales están dotadas del arte de pesca y de una embarcación con motores internos; y las menores (UEM), por pescadores que no cuentan con embarcaciones. Se censaron veinticinco embarcaciones, de las cuales el 92% (veintitrés) están fabricadas de madera, 1 de fibra de vidrio (4%) y una de una combinación de estos materiales (4%). De las embarcaciones construidas en madera, veinte son denominadas boqueras (87%), dos son canoas (8.7%) y una es cayuco (4.3%). Las primeras utilizan motor interno, que van de 40 a 120 HP. En el sector de Bocas de Ceniza, las boqueras son las que dirigen su esfuerzo a los tiburones, empleando principalmente el trasmallo y con menor frecuencia el palangre y la línea de mano. Los trasmallos utilizados se caracterizaron por tener tamaños de malla entre 12.7cm y 17.78 cm. En algunas UEP se observó que el uso del trasmallo fue calado simultáneamente con otros artes (palangre y línea de mano). Durante el periodo de estudio, se observaron dieciocho especies de tiburones agrupados taxonómicamente en seis órdenes, nueve familias y diez géneros; así mismo, se observaron cinco especies de rayas y una quimera. Se registró por primera vez para el Caribe colombiano continental la presencia del tiburón Heptranchias perlo y está por confirmar una nueva especie de tiburón ángel Squatina sp. para la ciencia. En total se estimaron 119538 kg, de los cuales el 6.7% correspondió a tiburones. De los tiburones desembarcados, la mayor captura fue de cazón picudo antillano Rhizoprionodon porosus con el 23% del grupo, seguido por la cornuda común Sphyrna lewini y el tiburón sedoso Carcharhinus falciformis, con 22.4% y 17.2%, respectivamente. En total se estimaron 1777 faenas de pesca, de las cuales 1334 fueron para trasmallo. La captura por unidad de esfuerzo (CPUE) de trasmallo discriminado por especie de tiburón varío tanto espacial como temporalmente, observándose los valores más altos al inicio del estudio y disminuyendo gradualmente a finales. R. porosus presentó el valor más alto de CPUE con 6.5 kg/faena durante febrero. Se confirmó que en general, la actividad pesquera tiene un nivel tecnológico bajo, fuertemente dependiente del clima y de la disponibilidad del recurso pesquero costero, en la cual los tiburones son aprovechados en su totalidad y, aunque aparentemente representan una menor ganancia, de ellos derivan muchos subproductos que motivan su captura. Debido a las limitaciones de este estudio, y a la gran cantidad de información bioecológica y pesquera faltante sobre la actividad pesquera durante todo el año, se encontró que existe la necesidad de un mayor esfuerzo investigativo en el área para garantizar un mejor conocimiento del estado de los tiburones para ayudar a su manejo y conservación

- by Vladimir Puentes
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- Fisheries Science, Fisheries, Fisheries Management, Fisheries Biology

Los tiburones, rayas y quimeras son especies acuáticas agrupadas en la Clase Condrictios, caracterizadas por tener
esqueleto de cartílago, escamas placoideas y órganos copuladores externos en los machos (llamados cláspers).
Estos animales ocupan diversos ambientes tanto marinos, como estuarinos y dulceacuícolas, y diversas zonas,
desde la zona tropical a las zonas polares. En Colombia, varias especies de tiburones y rayas pueden ser
observadas in situ en diversos ambientes, teniendo los mismos un gran valor ecológico y turístico. Así mismo,
muchos de ellos (incluyendo las quimeras) son susceptibles de ser capturados en diversas pesquerías, teniendo
algunos de ellos valor comercial y otros siendo simplemente descartados por carecer del mismo.
De cualquier forma, Colombia, considerado un país megadiverso tanto por las flora como por la fauna acuática y
terrestre, lo es así mismo por la diversidad de especies de condrictios, contando con 126 especies confirmadas para
las áreas marinas y dulceacuícolas de Colombia, correspondientes a 63 especies de tiburones, 60 de rayas y 3 de
quimeras.
Esta guía está dirigida tanto a la comunidad en general, con miras a divulgar la biodiversidad de este grupo de
animales en nuestro país, así como a estudiantes, investigadores, observadores, pescadores, administradores
locales y regionales pesqueros y ambientales que desarrollan diversas actividades relacionadas con los condrictios.
Así, se espera aportar en el adecuado aprovechamiento y manejo de estos recursos, como parte integral del Plan de
Acción Nacional para la conservación y manejo de tiburones, rayas y quimeras de Colombia (PAN-Tiburones),
liderado por la autoridad pesquera, INCODER.

- by Vladimir Puentes
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- Fisheries, Taxonomy, Marine Science, Shark conservation

Hiu karet (Prionace glauca) adalah hiu pelagis yang menjadi target tangkapan nelayan artisanal Tanjung Luar dan umumnya tertangkap di Samudera Hindia Selatan Nusa Tenggara. Penelitian ini bertujuan untuk mengetahui sebaran ukuran dan beberapa parameter populasi hiu karet (Prionace glauca) yang tertangkap di perairan selatan Nusa Tenggara. Analisis dilakukan terhadap 1.414 ekor hiu karet yang tertangkap rawai hanyut di selatan Nusa Tenggara dan didaratkan di Tanjung Luar, Lombok Timur selama periode 2014 – 2016. Analisis data dilakukan secara deskriptif dan beberapa parameter populasi diduga menurut rumus empiris Froese & Binohlan (2000). Hasil penelitian menunjukkan sebaran ukuran panjang total hiu karet berkisar antara 95 – 383 cm (jantan) dan 113 – 333 cm (betina) dengan rerata ukuran yang tertangkap tidak berbeda nyata. Nisbah kelamin didominasi oleh hiu karet jantan dan telah matang kelamin. Dugaan terhadap beberapa parameter adalah: nilai L∞ antara 333,02 - 385,59 cm dengan Lm jantan antara 187,21 – 215 cm dan betina 139,82 – 159,34 cm. Sebanyak 39,96 – 44,71% hiu karet tertangkap pada panjang optimumnya sehingga ada kecenderungan tangkap lebih.

- by Agus Arifin Sentosa and +1
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- Fisheries Science, Fisheries, Fisheries Management, Fish Biology

Hiu macan atau tiger shark (Galeocerdo cuvier Peron & Lesuer, 1822) banyak tertangkap di perairan Samudera Hindia. Status konservasinya masuk dalam Daftar merah IUCN dan hampir terancam (NT). Tujuan penelitian adalah untuk mendapatkan informasi parameter populasi hiu macan di perairan Samudera Hindia bagian Selatan Nusa Tenggara Barat. Penelitian dilakukan di tempat pendaratan ikan Tanjung Luar, Lombok Timur pada bulan Januari sampai dengan Desember 2016 menggunakan metode survei. Hasil penelitian terhadap 808 ekor ikan contoh menunjukkan bahwa kisaran panjang total untuk hiu macan (Galeocerdo cuvier) antara 116 - 400 cmTL. Perbandingan kelamin ikan hiu macan jantan dan betina dalam keadaan tidak seimbang, dengan jumlah betina lebih besar. Estimasi panjang asimtotik (L∞) sebesar 420 cmTL dengan laju pertumbuhan (K) sebesar 0,260/tahun, laju kematian total (Z) sebesar 1,10/tahun, laju kematian alamiah (M) sebesar 0,35/tahun serta laju kematian akibat penangkapan (F) sebesar 0,75/tahun. Estimasi laju eksploitasi sudah berada pada penangkapan yang berlebih (E = 0,68) oleh karena itu perlu dilakukan tindakan pengelolaan agar pemanfaatannya tetap lestari.
KATA KUNCI : parameter, populasi, hiu macan, Galeocerdo cuvier, Nusa Tenggara Barat

- by Agus Arifin Sentosa
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- Fisheries Science, Fisheries Management, Fish Biology, Fisheries Biology

In the history of Western philosophy, before Heidegger, we see that the question of the animal was not given much thought, or perhaps deliberately ignored. Many prominent philosophers had maintained an anthropocentric position, in which the status of the animal is lower than that of humans. The question of the animal in modern continental thought is founded on Heidegger's acknowledgement of the animal being. This essay uses the shark species to analyse the progression of the question of the animal from Heidegger to modern day philosophers. The Cartesian tradition held that animals do not have souls and therefor do not feel pain.

- by Melanie A Dunne
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- Animal Ethics, Continental Philosophy, Martin Heidegger, Jacques Derrida
- by Victor Peddemors and +1
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- Shark conservation, Sharks, Biology, ecology and fishery of sharks and their relatives
- by Jennifer Marshall and +1
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- Shark conservation, Sharks, Biology, ecology and fishery of sharks and their relatives
- by Maria Faria and +1
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- Environmental Education, Biology, ecology and fishery of sharks and their relatives

In this paper I present the results of an analysis of prehistoric archaeological faunal remains from a coastal site near Osprey, FL. Notably, shark dermal denticles (scales) as well as remains from four shark species (teeth and vertebrae) and one ray, with 33 species of bony fish and 37 species of molluscan remains were found. One bone fragment of a West Indian Monk seal was also found in a human burial.

A new species of Squatina, S. david, is described from the Colombian Caribbean. The new species differs from all the western North Atlantic angel sharks by lacking a mid-dorsal line of thorns or enlarged dermal denticles, by having an eye-spiracle distance larger than 1.5 times eye diameter, and each nasal flap with two rod-like barbels. Coloration is grayish to brownish yellow, males are dark-spotted, females have abundant whitish spots. Squatina david is nested within the American clade of angel sharks, being the sister species to the Brazilian species.

This study proposes length relationship equations to determine total length of four species of sharks (Carcharhinus falciformis, Mustelus lunulatus, Sphyrna lewini and Carcharhinus limbatus) based on trunk lengths (TrL) and interdorsal lengths (IL) caughtlationship was acceptable for C. falciformis (r 2 = .69) and C. limbatus which presented a good relationship (r 2 = .81) where most specimens were juveniles; the same trend was found for S. lewini (r 2 = .96). The TL-TrL relationship estimated for species caught in the Colombian Pacific was significant for C. falciformis (r 2 = .98) and for M. lunulatus (r 2 = .84); however, for S. lewini this relationship was low (r 2 = .55). Results indicate this is a useful tool for fishery statistics and fishery management for elasmobranch species of the Eastern Tropical Pacific.

- by Carlos Julio Polo-Silva and +1
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- Fisheries Science, Fisheries, Fisheries Management, Fish Biology

RESUMEN Se amplía la distribución geográfica del " tiburón de " siete branquias " Heptranchias perlo (Hexanchidae: Hexanchiformes) para el Caribe continental colombiano, a partir de tres ejemplares capturados con redes de enmalle de monofilamento de 13, 10 y 9 cm, entre 80 y 100 m de profundidad, en el área de Puerto Colombia y Sabanilla, departamento de Atlántico, que registraron 1000, 980, y 978 mm. de longitud total, con pesos de 3, 3 y 2.75 kg, respectivamente; siendo los animales de Puerto Colombia hembras preñadas y el espécimen de Sabanilla una hembra madura no preñada. ABSTRACT Geographical extension of the sharpnose sevengill shark Heptranchias perlo Bonaterre (Hexanchiformes: Hexanchidae) for the continental Colombian Caribbean. The geographic distribution of the sharpnose seven gill shark Heptranchias perlo (Hexanchidae: Hexanchiformes) is expanded for the Colombian mainland Caribbean, from three specimens caught with monofilament gillnets of 13, 10 and 9 cm between 80 and 100 m depth, in the area between Puerto Colombia and Sabanilla, Atlántico. Specimens measured 1000, 978-980 mm total length; and a weight of 3, 3 and 2.75 kg respectively; sharks from Puerto Colombia were pregnant females and the Sabanilla specimen a non-pregnant but mature female .

White sharks (Carcharodon carcharias, WS henceforth) are globally and regionally threatened. Understanding their patterns of abundance and connectivity, as they relate to habitat use, is central for delineating conservation units and identifying priority areas for conservation. We analyzed mitochondrial data to test the congruence between patterns of genetic connectivity and of individual movements in the Northeastern Pacific (NEP) and to trace the matrilineal origin of immature WS from coastal California and Baja California to adult aggregation areas. We analyzed 186 mitochondrial control region sequences from sharks sampled in Central California (CC; n = 61), Southern California Bight (SCB; n = 25), Baja California Pacific coast (BCPC; n = 9), Bahía Vizcaíno (BV; n = 39), Guadalupe Island (GI; n = 45), and the Gulf of California (GC; n = 7). Significant mitochondrial differentiation between adult aggregation areas (CC, GI) revealed two reproductive populations in the NEP. We found general concordance between movement patterns of young and adult WS with genetic results. Young sharks from coastal California and Baja California were more likely born from females from GI. Mitochondrial differentiation of young-of-the-year from SCB and BV suggests philopatry to nursery areas in females from GI. These results provide a genetic basis of female reproductive behavior at a regional scale and point to a preponderance of sharks from GI in the use of the sampled coastal region as pupping habitat.These findings should be considered in Mexican and US management and conservation strategies of the WS NEP population.

- by Axayácatl Rocha-Olivares and +1
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- Population Genetics, Marine Conservation, Great white shark, Mitochondrial DNA

The paper confirms the presence of Alopias superciliosus in the Tyrrhenian Sea, giving useful information for a
species assessed as “vulnerable” worldwide and “data deficient” for the Mediterranean Sea by IUCN. In the stomach of this
shark, 25 specimens of Pseudophyllidea, 4 of Trypanorhyncha and 3 of Anisakis spp. were found. In the gut, the presence
of 20 specimens of Litobothrium spp. was observed. Since this is the first evidence of the presence of the genus
Litobothrium in the Mediterranean Sea, the paper demonstrates a range expansion of this parasite from the Pacific.

Hiu merak bulu adalah salah satu jenis hiu sebagai komoditas perikanan yang dimanfaatkan secara optimal di perairan selatan Nusa Tenggara, namun informasi ilmiah terkait hiu tersebut masih terbatas. Penelitian ini bertujuan untuk mengkaji pola pertumbuhan dan faktor kondisi hiu merak bulu, Carcharhinus brevipinna. Penelitian dilakukan pada bulan Januari – Desember 2016 dengan melakukan pengumpulan data hasil tangkapan rawai dan jaring insang. Data yang dihimpun meliputi panjang, berat dan jenis kelamin hiu yang dicatat secara langsung dan dibantu oleh enumerator. Metode analisis dilakukan secara deskriptif dengan kondisi hiu ditentukan berdasarkan faktor kondisi relatif yang diperoleh dari hubungan panjang-beratnya. Hasil penelitian menunjukkan pola pertumbuhan hiu merak bulu jantan dan betina bersifat alometrik negatif. Faktor kondisi relatif hiu jantan berkisar antara 0,206 – 2,225 dan betina antara 0,237 – 3,361. Faktor kondisi hiu merak bulu tidak berbeda antar jenis kelamin dan waktu penangkapan, namun berbeda antar kelas ukuran panjang.
Kata kunci: Hiu merak bulu, Carcharhinus brevipinna, hubungan panjang berat, faktor kondisi, Tanjung Luar

- by Agus Arifin Sentosa
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- Fisheries Science, Fisheries, Fisheries Management, Fish Biology
- by Rodolfo Vogler and +1
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- Sharks, Biology, ecology and fishery of sharks and their relatives

Top-predators may be extremely vulnerable to environmental contaminants, such as organochlorines (OCs) and polycyclic aromatic hydrocarbons (PAHs), mostly because of their position in the trophic web. In this study, the use of skin biopsy is proposed as a sensitive non-lethal technique for the toxicological assessment of white shark (Carcharodon carcharias) living off the South African coasts. In 2012, 15 specimens of great white shark were sampled in the waters off Dyer Island and Geyser Rock. Then OCs and PAHs were extracted from muscle and biomarkers techniques for the evaluation of the cytochrome P4501A (CYP1A), Vitellogenin (Vtg) and Zona Radiata Proteins (Zrp) in the skin have been developed for the first time. The results showed levels of OCs higher than those found in the literature, ranging in ng/g dry weight (d.w.) from 6.80 to 21.26 for hexachlorobenzene (HCB), from 86.72 to 1416.97 for DDTs and from 379.76 to 11284.31 for polychlorinated biphenyls (PCBs). Furthermore, the values of both pp'DDE/pp'DDT and pp'DDE/DDTs ratios suggest a recent DDT introduction in the environment, probably related to its use against malaria during the period 2000-2005 in KwaZulu-Natal. However, PAHs showed the highest levels, almost double compared to OCs, almost certainly due to the big oil traffic present in South Africa. Regarding biomarkers results, important responses for CYP1A have been highlighted, possibly due to a contamination by planar compounds such as PAHs. Finally, the preliminary results of Vtg and Zrp, biomarkers of estrogenic effects, showed the presence of these proteins in sexually immature females and males.

- by Primo Micarelli
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- Great white shark, Shark conservation, Fossil sharks, Shark Biology

A research has been done to determine some biological aspects of Western Longnose Spurdog (Squalus edmundsi) from the Eastern Indian Ocean Fishing Region in Indonesia (WPP 573). A total of 1797 samples were recorded from bottom longline fisheries at Tanjung Luar, Lombok from July 2015 to November 2016 by a trained enumerator. The study revealed that Selat Alas and the south west of Sumbawa waters are the most fished areas in the region for this species, with the peak fishing season may occur from January to March. The average catch rate of S. edmundsi was about 8 individuals per boat. The size of sharks varied from 470 mm to 1150 m total length (TL), with average size was 723.6±111.5 mm. Size distributions and sex ratio between females and males were significantly different, indicating a sexual dimorphism. This study revealed a fact that there was no seasonal pattern in the reproductive cycle of S. edmundsi in this region, which means the parturition may occur throughout the year. Analysis on its population status showed that this species was very susceptible to overfishing. This condition should be responded by the government through management actions for its fishery.

- by Fahmi LIPI and +1
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- Marine Biology, Fisheries, Fisheries Management, Fish Biology

Tanjung Luar merupakan sentra penangkapan hiu di Indonesia karena jumlah tangkapan hiu yang didaratkan jauh lebih banyak dari semua tempat penangkapan hiu di Indonesia. Penelitian ini bertujuan untuk mengetahui hasil tangkapan dan kelimpahan relatif beberapa jenis hiu yang didaratkan di Tanjung Luar, Lombok. Data diperoleh melalui wawancara dan catatan enumerator di Tanjung Luar, Lombok Timur pada bulan Januari – November 2015. Analisis data dilakukan secara deskriptif dan disajikan sebagai persentase kelimpahan relatif. Hasil menunjukkan bahwa tangkapan hiu pada tahun 2015 berfluktuasi setiap bulannya dengan puncak hasil tangkapan terjadi pada bulan September 2015. Total tangkapan hiu sebesar 237,5 ton dengan rerata tangkapan sebesar 1,4 ton/hari. Komposisi tangkapan terdiri atas 28 spesies yang terbagi dalam sebelas famili. Carcharhinus falciformis (42,06%), Prionace glauca (10,45%), dan Carcharhinus limbatus (10,31%) secara berurutan merupakan hiu predominan dengan kelimpahan relatif lebih besar dari 10%.

- by Agus Arifin Sentosa
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- Fisheries Management, Shark, Shark conservation, Sharks

The present paper reports the abundance and biomass of Dasyatis centroura (Mitchill, 1815), D. marmorata (Steindachner, 1892), D. pastinaca (Linnaeus, 1758), and D. tortonesei Capapé, 1975 at various depth levels and seasons in the Gulf of Antalya, and total length-weight (TL-W), disc length–weight (DL-W) and disc width–weight (DW-W) relationship of 391 individuals of D. pastinaca, 21 individuals of D. marmorata, and five individuals of D. centroura, caught in trawling surveys. A total of 116 hauls were carried out, between August 2009 and April 2010 seasonally in the Gulf of Antalya, at six stations and six depth levels (25, 50, 75, 100, 150, 200 m) using a commercial bottom trawl. Dasyatis species were sampled from 65 hauls and the frequency of occurrence was 56.03% for D. pastinaca, 11.21% for D. marmorata, 2.59% for D. centroura and 0.86% for D. tortonesei. The overall mean abundance and biomass was 55.32 ind./km 2 and 107.53 kg/km 2 for D. pastinaca; 2.54 ind./km 2 and 2.56 kg/km 2 for D. marmorata, 0.50 ind./km 2 and 25.97 kg/km 2 for D. centroura and 0.25 ind./km 2 and 1.34 kg/km 2 for D. tortonesei. The general TL-W, DL-W and DW-W were described by the equations: W = 0.023*TL 2.76 ; W = 0.0999*DL 2.74 and W = 0.037*DW 2.97 for D. pastinaca; W = 0.002*TL 3.23 ; W = 0.034*DL 3.02 and W = 0.0045*DW 3.59 for D. marmorata; and W = 0.00001*TL 4.04 ; W = 1.481*DL 2.16 and W = 0.141*DW 2.59 for D. centroura.

- by Elif Özgür
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- Marine Biology, Marine Ecology, Fisheries, Fisheries Biology
- by Gaston Bazzino Ferreri and +1
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- Biology, ecology and fishery of sharks and their relatives

El PAN-Tiburones de Colombia cita la importancia de realizar estudios que generen información sobre las poblaciones de tiburones en el territorio nacional, en el Caribe Colombiano Rhizoprionodon porosus es la especie de tiburón más frecuente en los registros pesqueros, sin embargo, se desconoce la dinámica de sus poblaciones, por lo cual se planteó un estudio para comprender algunas de estas dinámicas que presenta la población de esta especie en Isla Fuerte Caribe Sur Colombiano. Para ello se recopilaron registros pesqueros de la zona desde el 2004 y adicionalmente se realizaron muestreos entre el 2011 y el 2013 construyendo una base de datos de más de 300 tiburones, por medio de la cual se analizaron dinámicas de la población.
Para esta especie se encontró una talla de madurez sexual de 63 cm LT para machos y 60 cm LT para hembras, el número de embriones por hembra varió entre 1 y 3, encontrado una relación entre talla y el número de embriones, también se infirió un tiempo de gestación de 11 a 12 meses. La proporción sexual de la población fue de 2,3M:1H la cual se vio reflejada en la proporción sexual de los embriones con los mismos valores.
La estructura poblacional se concentró en estadíos avanzados, teniendo una distribución de tallas para machos de 39 a 89 cm, mientras que la de hembras fue de 43 a 110 cm LT. Se encontró una relación entre abundancia y profundidad. Se determinó que los machos se mantienen cerca a la Isla durante todo el año, entretanto, las hembras presentan migraciones reproductivas en mayo. Los tiburones de tallas adultas presentan las mayores abundancias de marzo a septiembre y el resto de los meses se registran principalmente individuos de tallas juveniles y neonatos. Se encontró que las tallas máximas han disminuido y se observó una segregación sexual y por estadíos.
La importancia de los caladeros ha variado a través de los años, donde los caladeros cercanos han ido perdiendo importancia, igualmente el número de caladeros ha aumentado. La importancia de R. porosus en la pesca artesanal de tiburón ha aumentado debido a que las otras especies han disminuido sus abundancias. Se observó que hay una pesca dirigida al tiburón en la que no hay una regulación de artes de pesca ni de tallas mínimas.

Sharks are fished for human consumption in Colombia, and fins are exported illegally to international markets. The goal was to identify differences in total mercury (THg) concentrations in fins and muscles of shark species seized in the Buenaventura port (Colombian Pacific), and to assess potential human health risks related to shark consumption. Seven species were considered in this study: Pelagic Thresher (Alopias pelagicus), Pacific Smalltail Shark (Carcharhinus cerdale), Brown Smoothhound (Mustelus henlei), Sicklefin Smoothhound (Mustelus lunulatus), Scalloped Bonnethead (Sphyrna corona), Scalloped Hammerhead (Sphyrna lewini), and Bonnethead Shark
(Sphyrna tiburo), and THg was analyzed in shark tissues. 24% muscle samples concentrations were above international recommended limits for human consumption, especially for A. pelagicus and S. lewini. Stable isotopes (δ13C and δ15N) analysis showed a foraging overlapping in coastal habitats, where overfishing usually occurs. This study provides useful scientific information to develop management plans for sharks in Colombia and neighboring countries.

bluntnose six-gill shark (74 individuals) are reported with a greater intensity, possibly due to a higher public awarness on the conservation status of sharks, and consequent development of monitoring programs. Unfortunately, MEDLEM does not cover with equal sampling effort all mediterranean sectors. Scientific monitoring in the south eastern Mediterranean is generally lower than in the northern European sectors and therefore the absence of some species from these regions in our database does not imply their actual absence from the area. From 1800 to 1870 the average recording rate is 1.2 specimens/year, and then up to 1990 average recording grows to 5 specimens/year, mainly due to bibliographic sources. In the last 20 years, the recording rate has further increased to 59 specimens/year. The geographical distributions of the main species recorded are represented as well as some consideration on fishing gears and size structure for the area where most data are available.

Komoditas hiu dan pari merupakan hasi tangkapan utama yang didaratkan di Tempat Pendaratan Ikan Tanjung Luar. Penangkapan hiu dan pari telah menjadi isu internasional karena sifat biologinya yang rentan terhadap penangkapan berlebih. Penelitian ini bertujuan untuk menganalisis tingkat kerentanan penangkapan hiu dan pari yang telah masuk dalam Appendiks CITES yang didaratkan di Tanjung Luar, Lombok Timur. Penelitian dilakukan selama Januari – November 2016 dengan data tangkapan berasal dari catatan enumerator. Analisis kerentanan dilakukan menggunakan perangkat lunak PSA (Productivity and Susceptibility Analysis). Hasil menunjukkan indeks kerentanan tangkapan hiu dan pari Appendiks CITES berkisar antara 1,92 – 2,24 dengan kerentanan yang tinggi pada hiu martil (Sphyrna spp.), hiu kejen (Carcharhinus falciformis) dan hiu tikus (Alopias spp.). Potensi keberlanjutan sumber daya hiu dan pari Appendiks II CITES relatif rendah sehingga diperlukan pengaturan dalam upaya penangkapannya.

- by Agus Arifin Sentosa
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- Fisheries, Fisheries Management, Shark, Shark conservation

The relationship of body weight and total length (L T) of Mustelus schmitti in southern Patagonia was different between sexes. Changes in maturity stages in males appear at larger sizes in Ría Deseado specimens than in the Mar del Plata area. Mature females ranged from 795 to 913 mm while all male specimens >759 mm L T were mature. The data suggest that mating occurs before parturition, with simultaneous ovulation. The diet of adult M. schmitti was mainly carcinophage and the diet of young-of-the-year and adults differed. The young-of-the-year use the Ría Deseado as a pupping area.

Such study, conducted at Acquario di Cattolica (Rimini, Italy), lasted six months of observations on Chiloscyllium punctatum reproductive biology. It is an oviparous species present in many aquaria around the world, but the fishing effort, habitat destruction and constant samples taking have led to a drop in the number of wild populations (IUCN red list). Looking at the current low level of reproductive standard protocols, we tried to collect the greatest number of useful information in order to obtain a reproductive protocol. The couple of adults, cohabiting in a tank with other species, were breeding and maintained in stable environmental conditions (i.e. T °C, % and pH). When deposition occurred, the eggs were moved in 5 expository trays (Themes-5), ex-novo settled up. These trays allowed the monitoring of embryonic development till hatching 120 ± 10 days post deposition (dpd). Newborns were measured by total length (TL, cm) to quantify the growth (Von Bertalanffy Growth Function, VBGF) and the growth rates (GR), therefore weaned from yolk sac. They were feeded 3 times per week, by a specific diet based on shrimp (Pandalus borealis), capelin (Mallotusvillosus), codfish (Merlucciusmerluccius) and mackerel (Scomberscombrus). Besides, it was setted a light gradient (1 lx <x< 10 lx) on Themes-5 to assess the light influence on newborns growth. The VBGFs underlined significant differences about sizes and timelines to achieve sexual maturity between male and females (p< 0.05). Concerning different light conditions, we underlined no significant differences (p> 0.05). Shrimp (P. borealis: 3 cal/1 gr) resulted the food with the best performance. The adults produced 33 newborns depositing 2 eggs per week. These observations have made possible to provide useful information on shark deposition, hatching, diet and newborn growth.

- by Victor Peddemors and +1
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- Shark conservation, Sharks, Biology, ecology and fishery of sharks and their relatives