Data from: Discovery of a multi-species shark aggregation and parturition area in the Ba Estuary, Fiji Islands

Sampling event Observation
最新バージョン Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node により出版 8月 2, 2024 Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node
公開日:
2024年8月2日
ライセンス:
CC-BY 4.0

DwC-A形式のリソース データまたは EML / RTF 形式のリソース メタデータの最新バージョンをダウンロード：

DwC ファイルとしてのデータ ダウンロード 102 レコード English で (21 KB) - 更新頻度: not planned
EML ファイルとしてのメタデータ ダウンロード English で (17 KB)
RTF ファイルとしてのメタデータ ダウンロード English で (13 KB)

説明

Population declines in shark species have been reported on local and global scales, with overfishing, habitat destruction and climate change posing severe threats. The lack of species-specific baseline data on ecology and distribution of many sharks, however, makes conservation measures challenging. Here we present a fisheries-independent shark survey from the Fiji Islands, where scientific knowledge on locally occurring elasmobranchs is largely still lacking despite the location’s role as a shark hotspot in the Pacific. Juvenile shark abundance in the fishing grounds of the Ba Estuary (north-western Viti Levu) was assessed with a gillnet- and longline-based survey from December 2015 to April 2016. A total of 103 juvenile sharks identified as blacktip Carcharhinus limbatus (n = 57), scalloped hammerhead Sphyrna lewini (n = 35), and great hammerhead Sphyrna mokarran (n = 11) sharks were captured, tagged, and released. The condition of umbilical scars (68 % open or semi-healed), mean sizes of individuals (± SD) (C. limbatus: 66.5 ± 3.8 cm, S. lewini: 51.8 ± 4.8 cm, S. mokarran 77.4 ± 2.8 cm), and the presence of these species over recent years (based on fishermen interviews), suggest that the Ba Estuary area is a critical habitat for multiple species that are classified as “Near Threatened” or “Endangered”. Specifically, the area likely acts as a parturition ground over the studied period, and potentially as a subsequent nursery area. We identified subareas of high abundance and found that temperature, salinity and depth acted as small-scale environmental drivers of shark abundance. The data suggests a tendency for species-specific spatial use, both horizontally (i.e. between sampling areas) and vertically (i.e. across the water column). These results enhance the understanding of shark ecology in Fiji and provide a scientific basis for the implementation of local conservation strategies that contribute to the protection of these threatened species.

データ レコード

この sampling event リソース内のデータは、1 つまたは複数のデータ テーブルとして生物多様性データを共有するための標準化された形式であるダーウィン コア アーカイブ (DwC-A) として公開されています。 コア データ テーブルには、102 レコードが含まれています。

拡張データ テーブルは2 件存在しています。拡張レコードは、コアのレコードについての追加情報を提供するものです。 各拡張データ テーブル内のレコード数を以下に示します。

Event (コア)
102
ExtendedMeasurementOrFact 
961
Occurrence 
103

この IPT はデータをアーカイブし、データ リポジトリとして機能します。データとリソースのメタデータは、 ダウンロード セクションからダウンロードできます。 バージョン テーブルから公開可能な他のバージョンを閲覧でき、リソースに加えられた変更を知ることができます。

バージョン

次の表は、公にアクセス可能な公開バージョンのリソースのみ表示しています。

引用方法

研究者はこの研究内容を以下のように引用する必要があります。:

Vierus T, Gehig S, Brunnschweiler J M, Glaus K, Zimmer M, Marie A D, Rico C (2024). Data from: Discovery of a multi-species shark aggregation and parturition area in the Ba Estuary, Fiji Islands. Version 1.0. Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node. Samplingevent dataset. https://nzobisipt.niwa.co.nz/resource?r=ba_estuary_sharks&v=1.0

権利

研究者は権利に関する下記ステートメントを尊重する必要があります。:

パブリッシャーとライセンス保持者権利者は Southwestern Pacific Ocean Biogeographic Information System (OBIS) Node。 This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.

GBIF登録

このリソースは GBIF に登録されていません。

キーワード

Samplingevent; Observation

連絡先

Tom Vierus
  • 最初のデータ採集者 ●
  • 連絡先
  • Researcher
Leibniz Center for Tropical Marine Ecology
Bremen
DE
Stefan Gehig
  • 最初のデータ採集者
  • Researcher
Leibniz Center for Tropical Marine Ecology
Bremen
DE
Juerg M. Brunnschweiler
  • 最初のデータ採集者
  • Researcher
University of the South Pacific
  • PO Box 1168
Suva
FJ
Kerstin Glaus
  • 最初のデータ採集者
  • Researcher
University of the South Pacific
  • PO Box 1168
Suva
FJ
Martin Zimmer
  • 最初のデータ採集者
  • Researcher
University of Bremen
Bremen
DE
Amandine D. Marie
  • 最初のデータ採集者
  • Researcher
University of the South Pacific
  • PO Box 1168
Suva
FJ
Ciro Rico
  • メタデータ提供者 ●
  • 最初のデータ採集者
  • Researcher
University of the South Pacific
  • PO Box 1168
Suva
FJ

地理的範囲

Ba Estuary, Viti Levu, Fiji

座標（緯度経度） 南 西 [-17.465, 177.594], 北 東 [-17.42, 177.694]

生物分類学的範囲

Sharks

Species Carcharhinus limbatus (Blacktip shark), Sphyrna lewini (Scalloped hammerhead shark), Sphyrna mokarran (Great hammerhead shark)

時間的範囲

開始日 / 終了日 2015-12-02 / 2016-04-18

収集方法

Based on the results of a pilot survey, seven 1.13 km2 circular sampling areas in the immediate vicinity of the river mouth were selected. Each sampling area featured contrasting environmental features (e.g., depth, distance to mangroves, turbidity) and overlapped with areas that local fishermen identified as having higher shark abundances. Sampling areas 1–6 contained 10 sites each, and area 7 contained nine sampling sites.

Study Extent The study was conducted in a shallow bay environment (depth < 15 m) in north-western Viti Levu, the main island of the Republic of Fiji. The sampled area around the Ba River mouth is part of a larger bay that is sheltered from the open sea by patches of fringing reefs and from the mainland by mangroves. The sea bottom predominantly consists of muddy substrate and seagrass beds. The area is under strong tidal influence, with a tidal range of approximately 2 m (www.tide-forecast.com, 2016). There is activity by artisanal and subsistence fishermen from surrounding villages in the estuary. While sharks are by tradition not explicitly targeted in fishing operations, they regularly occur as low-value bycatch.

Method step description:

  1. The main shark-fishing survey was conducted on 26 days from December 2015 to April 2016. Bottom-set gillnets and longlines were set at depths ranging from 1 to 15 m in the seven sampling areas, with a total of 73 and 30 deployments, respectively. All deployments were carried out between 18:00 and 02:00 from a 7 m fiberglass boat with a 40 HP engine. Two assistants and a captain were present at all times. Bait used on longlines consisted predominantly of Indian mackerel (Rastrelliger kanagurta), and occasionally of red snapper (Lutjanus argentimaculatus), squid (Loligo sp.), and mullet (Mugil cephalus). Up to two gillnets (100 m length and 3 m width, ~10 cm mesh size) were deployed simultaneously with a soak time of 1–6 hr. To minimize animal stress and mortality, gillnets were regularly checked in intervals of 15–25 min. When feasible, a longline (75 m) with 27 hooks was additionally deployed at the same sampling sites to assess potential catch differences attributed to gear selectivity. Distance between gangions attached to the floater line varied from 2.4 to 2.8 m. Gangion length ranged between 0.6 and 3 m, with the last 0.5 m consisting of 1.5 mm steel wire and a baited 13″ circle hook. In total, fishing effort ranged from 6 to 10.36 hr (longline) and 15 to 23.08 hr (gillnet) per sampling area. Total soak time of gillnet and longline deployments varied from 30 min to 6 hr, and from 45 min to 3 hr, respectively. Sampling effort was intended to be uniformly distributed among the seven sampling areas and ranged from 24.5 to 33.3 hr/area (mean: 28 ± 3 hr/area).

書誌情報の引用

  1. Vierus, Tom et al. (2019). Data from: Discovery of a multi-species shark aggregation and parturition area in the Ba Estuary, Fiji Islands [Dataset]. Dryad. https://doi.org/10.5061/dryad.77k3k6n
  2. Vierus, T., Gehrig, S., Brunnschweiler, J.M., Glaus, K., Zimmer, M., Marie, A.D. and Rico, C., 2018. Discovery of a multispecies shark aggregation and parturition area in the Ba Estuary, Fiji Islands. Ecology and Evolution, 8(14), pp.7079-7093. https://doi.org/10.1002/ece3.4230

追加のメタデータ

marine, harvested by iOBIS

代替識別子 https://nzobisipt.niwa.co.nz/resource?r=ba_estuary_sharks