標題：AZFP論文：基于滑翔機的浮游動物生物量密度估計：南極半島北部南極磷蝦（Euphausia superba）的漁業案例研究

Abstract

We compare estimates of krill density derived from gliders to those from contemporaneous and previous ship-based surveys. Our comparisons cover several temporal and spatial scales within two strata around the northern Antarctic Peninsula (off Cape Shirreff on the north side of Livingston Island and in the Bransfield Strait). Our objective is to explore the feasibility of using gliders to supplement or replace vessel-based surveys of fishery resources. We deployed two long-duration Slocum G3 gliders manufactured by Teledyne Webb Research (TWR), each equipped with a suite of oceanographic sensors and a three-frequency (38, 67.5, and 125 kHz, each single-beam) Acoustic Zooplankton Fish Profiler. We used the acoustic data collected by these gliders to estimate biomass densities (g·m?2 ) of Antarctic krill (Euphausia superba). The two gliders were, respectively, deployed for 82 and 88 days from midDecember 2018 through mid-March 2019. Off Cape Shirreff, glider-based densities estimated from two repeat small-scale surveys during mid-December and January were 110.6 and 55.7 g·m?2 , respectively. In Bransfield Strait, the glider-based estimate of biomass density was 106.7 g·m?2 during December–January. Contemporaneous ship-based estimates of biomass density, from a multi-ship broad-scale krill survey (Macaulay et al., 2019) restricted to the areas sampled by the gliders, were 84.6 g·m?2 off Cape Shirreff and 79.7 g·m?2 in Bransfield Strait during January. We compared two alternative krill-delineation algorithms (dB differencing and SHAPES); differences

between biomass densities estimated by applying these algorithms were small and ranged between 4 and 7%. Alternative methods of sampling krill length-frequency distributions (LFDs) (nets or predator diets), which are required to convert acoustic energy to biomass density, also influenced the glider-based results. In Bransfield Strait, net-based estimates of biomass density were 6% less than those based on predator diets. Off Cape Shirreff the biomass density of krill estimated from a net-based LFD was 20% greater than that based on predator diets. Development of a variance estimatorfor glider-based biomass surveys is ongoing, but our results demonstrate that fisheries surveys using acoustically-equipped gliders are feasible, can provide density estimates to inform management, and may be conducted at lower cost than ship surveys in some cases.

Keywords: gliders, Antarctic krill, fisheries surveys, fisheries acoustics, zooplankton

摘要：

我們將滑翔機得出的磷蝦密度估計值與同期和以前的船基調查結果進行了比較。我們的比較涵蓋了南極半島北部兩個地層內的幾個時間和空間尺度（利文斯頓島北側的希勒夫角和布蘭斯菲爾德海峽）。我們的目標是探索使用滑翔機補充或取代基于船只的漁業資源調查的可行性。我們部署了兩架由Teledyne Webb Research（TWR）制造的長時間Slocum G3滑翔機，每架都配備了一套海洋傳感器和一個三頻（38、67.5和125 kHz，每個單波束）聲學浮游動物魚類剖面儀。我們使用這些滑翔機收集的聲學數據來估算南極磷蝦（Euphausia superba）的生物量密度（g·m?2）。這兩架滑翔機分別從2018年12月中旬到2019年3月中旬部署了82天和88天。在Shirreff角附近，12月中旬和1月兩次重復的小規模調查估計的滑翔機密度分別為110.6和55.7 g·m?2。在布蘭斯菲爾德海峽，12月至1月期間，基于滑翔機的生物量密度估計為106.7 g·m?2。根據多船大規模磷蝦調查（Macaulay等人，2019）對滑翔機采樣區域的同期船基生物量密度估計值為1月份Shirreff角84.6 g·m?2，布蘭斯菲爾德海峽79.7 g·m-2。我們比較了兩種替代的磷蝦描繪算法（dB差分和SHAPES）；應用這些算法估算的生物量密度差異很小，在4%到7%之間。將聲能轉化為生物量密度所需的磷蝦長度頻率分布（LFD）采樣的替代方法（網或捕食者飲食）也影響了基于滑翔機的結果。在布蘭斯菲爾德海峽，基于凈生物量密度的估計值比基于捕食者飲食的估計值低6%。在舍里夫角附近，根據基于網的LFD估計的磷蝦生物量密度比基于捕食者飲食的生物量密度高20%。基于滑翔機的生物量調查的方差估計正在開發中，但我們的結果表明，使用配備聲學設備的滑翔機進行漁業調查是可行的，可以提供密度估計以告知管理層，并且在某些情況下可能比船舶調查成本更低。

關鍵詞：Glider 滑翔機、南極磷蝦、漁業調查、漁業聲學、浮游動物，AZFP 魚類浮游動物聲學剖面儀