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Entanglement and Drowning of a Magellanic Penguin(Spheniscus magellanicus) in a Gill Net Recorded by a Time-Depth Recorder in South-Central ChileAuthor(s): Klemens Pütz, Luciano Hiriart-Bertrand, Alejandro Simeone,Victoria Riquelme, Ronnie Reyes-Arriagada and Benno LüthiSource: Waterbirds, 34(1):121-125. 2011.Published By: The Waterbird SocietyDOI: http://dx.doi.org/10.1675/063.034.0117URL: http://www.bioone.org/doi/full/10.1675/063.034.0117

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121

Entanglement and Drowning of a Magellanic Penguin (Spheniscusmagellanicus ) in a Gill Net Recorded by a Time-depth Recorder in

South-central Chile

KLEMENS PÜTZ1,*, LUCIANO HIRIART-BERTRAND2, 3, ALEJANDRO SIMEONE3,VICTORIA RIQUELME4, RONNIE REYES-ARRIAGADA4, 5 AND BENNO LÜTHI6

1Antarctic Research Trust, Am Oste-Hamme-Kanal 10, 27432 Bremervörde, Germany

2Center for Advanced Studies in Ecology and Biodiversity (CASEB), Departamento de Ecología,Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile

3Universidad Andrés Bello, Departamento de Ecología y Biodiversidad, República 470, Santiago, Chile

4Instituto de Zoología, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile

5Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile

6Antarctic Research Trust, c/o Zoo Zürich, Zürichbergstr, 221, 8044 Zürich, Switzerland

*Corresponding author; E-mail: puetz@antarctic-research.de

Abstract.—Various mitigation measures have been implemented to reduce incidental seabird mortality in lon-gline and trawl fisheries but little attention has been given to artisanal fishing. In the 2008/09 breeding season, dur-ing a study of foraging of Humboldt, Spheniscus humboldti, and Magellanic Penguins, S. magellanicus, breeding onPuñihuil islets, southern Chile, a Magellanic Penguin equipped with a time-depth recorder became entangled andsubsequently drowned in a gill net set for Corvina Drum (Cilus gilberti). The device was returned by fishermen andthe data appear to be the first documented case of such a drowning in a marine, air-breathing vertebrate. Accordingto the data, while diving to a depth of more than 50 m, the bird became entangled and drowned, remaining below60 m for nearly 21 hours until the net was hauled. Although only a single incident is reported, there are indicationsthat incidental mortality of penguins, other seabirds and marine mammals is more common in artisanal fisheriesthan previously anticipated. Received 20 April 2010, accepted 5 July 2010.

Key words.—artisanal fishery, data-logger, entanglement, gill net, penguin mortality.

Waterbirds 34(1): 121-125, 2011

Approximately 80% of seabird speciesare in decline globally (Birdlife Interna-tional 2009). A major factor contributing tothis trend is mortality by drowning in fish-ing gear deployed in both commercial andartisanal fishing operations (Moreno et al.2006; Pütz and Poncet 2009; Zydelis et al.2009). Consequently, mitigation measureshave been developed to reduce albatrossand petrel bycatch in longline and trawlfishing (e.g. Cooper et al. 2006; Sullivan etal. 2006a; 2006b; Gonzáles-Zevallos et al.2007; Watkins et al. 2008). However, bycatchof seabirds other than Procellariiformes,such as gulls, shags and penguins, hasraised only local or regional, if any, atten-tion (Zydelis et al. 2009) with only anecdotalreports on penguin mortality due to coastalfishing operations (Gandini et al. 1999; Sim-eone et al. 1999; Yorio and Caille 1999; Dar-

by and Dawson 2000; Norman 2000; Majlufet al. 2002; Taylor et al. 2002).

The Puñihuil islets in south-central Chileare the only place where Humboldt (Spheniscushumboldti) and Magellanic (S. magellanicus)Penguins breed sympatrically (Simeone andSchlatter 1998). However, over the past de-cades breeding pair numbers have declined,bolstered at least partly by incidental mortalityin the unregulated gillnet fishery undertakenin the area (Skewgar et al. 2009). Therefore, astudy investigating potential interactions be-tween the penguins’ foraging behavior and theartisanal fishery was initiated. Here, we reporton one Magellanic Penguin equipped with atime-depth-recorder that became incidentallyentangled in a gill net and subsequentlydrowned. To our knowledge, this is the first re-ported case of an incidental mortality actuallyrecorded by a time-depth-recorder.

122 WATERBIRDS

METHODS

Field work was conducted between 11 Novemberand 15 December 2008 at the Natural Reserve “Puñihuilislets” (41°55.4’S, 74°2.3’W), located off the northwestcoast of Isla Grande de Chiloé, southern Chile. The is-lets consist of three small islands where ca. 80 Hum-boldt and ca. 460 Magellanic Penguin breeding pairsnest sympatrically between September and April.

In order to investigate the foraging behavior of sym-patrically breeding Humboldt and Magellanic Penguinsduring the breeding season, birds guarding chicks wereequipped with MK9 archival tags (Wildlife Computers,Redmond, USA). Devices were attached on the midlineof the back using black tape (tesa, Beiersdorf AG, Ham-burg, Germany) and glue according to the method de-scribed by Wilson et al. (1997). The whole process tookless than 15 min per bird.

The MK9 used weighed approximately 32 g, equiva-lent to ca. 1% of the mean penguin body mass, and theirmaximum dimensions were 88

× 18

× 18 mm with across-sectional area of 3.25 cm2, corresponding to about2% of the penguins’ body cross-sectional area. Theywere programmed with MK9HOST (Vers. 1.09.1022,Wildlife Computers), with a measurement interval of 3seconds. The devices were each equipped with a pres-sure sensor, a light sensor and a temperature sensor. Asaltwater switch prevented data being recorded while atthe surface. Temperature and light measurements werenot considered in this study.

For the purpose of this study, only the results ob-tained from a bird incidentally drowned in fishing gearare considered. The male Magellanic Penguin wasequipped with a MK9 on 28 November while broodingtwo chicks. The device, but not the penguin, was re-turned on 1 December by local fishermen who had re-moved it from the drowned bird in the net. Dive datawere analyzed using INSTRUMENT HELPER (Vers.1.0.55, Wildlife Computers). After correcting for a drift-ing surface level, the following dive parameters were re-corded for all dives

≥3 m: onset, duration, maximumdepth, descent and ascent rate. Times given are in localsummer time, which was GMT -3 hours.

RESULTS AND DISCUSSION

Analysis of the recorded dive data re-vealed that the first foraging trip of the Ma-gellanic Penguin started on 29 November2008 at 14:20 local summer time (Table 1).The bird returned to the colony on that dayat 22:20 and departed again on 30 Novem-ber at 06:00. The penguin showed continu-ous diving activity until 12:55 (Fig. 1), follow-ing a series of dives to depths greater than 50m. The last dive recorded was initially to adepth of 53 m, reached at 12:56, presumablythe time when entanglement occurred. Therecorded depth then increased continuouslyto 67 m (first reached at 21:00) and re-mained at this maximum depth ± 1 m fornearly 13 hours. The ascent phase started at09:55 on 1 December, lasted seven minutesuntil 10:03 and was characterized by shortpauses at depths of 52 m (60 secs), 38 m (30secs) and 22 m (15 secs) before reaching thesurface. Overall, descent and ascent rateswere 0.3 and 0.2 m/s, respectively, and thedive lasted 21 hrs 7 min in total.

To our knowledge, this is the first timethat entanglement and subsequent drown-ing of a marine, air-breathing vertebrate hasbeen recorded using a time-depth recorder.For several reasons, we are confident that thepenguin studied became entangled in a gillnet. First, the device was returned by a localfisherman, albeit without the penguin car-

Table 1. Summary of dive parameters (>3 m) of two foraging trips recorded from a Magellanic Penguin from Puñi-huil islets, Chile, drowned in a gill net. The second foraging trip and the last dive recorded where the bird may havedrowned are separated.

Trip 1 Trip 2 Last Dive

Duration (hrs) 8.0 6.8 21.1Mean depth (m) 20 22

Maximum 48 55 68

Vertical distance underwater (m) 8948 6602Mean dive duration (secs) 69 77

Maximum 156 141 21.1

Time spent underwater (hrs) 4.32 3.27 21.1(%) 54 48Mean descent velocity (m/s) 0.8 0.7 0.3

Maximum 1.5 1.8

Mean ascent velocity (m/s) 0.9 0.8 0.2Maximum 2 1.7

DROWNING OF A MAGELLANIC PENGUIN IN A GILL NET 123

cass, after being out at sea hauling gill nets.However, the fisherman stated that he hadfound the bird drowned in the net. Secondly,the ascent phase of the penguin’s diving pro-file was characterized by several periods with-out any changes in depth, unlikely to occurin a bird naturally ascending to the surface.Normally, descent and ascent rates weregreater than 1 m/s in dives deeper than 50 m(Pütz et al., unpubl. data), whereas in this in-stance the ascent rate, at 0.2 m/s, was muchlower. Thirdly, gill nets are commonly usedto catch Corvina Drum Cilus gilberti, hakeMerluccius spp., Cusk-eels Genypterus spp. andferal salmon around the Puñihuil islets(Sepulveda et al. 2007; Skewgar et al. 2009).Gill nets used are made of monofilament ny-lon strings and are kept in vertical positionby floats and anchors. The length of the netis variable (from 200 to 800 m) with a meshsize of 5 cm, although nets used to catch Cor-

vina Drum may have a mesh size of up to 20cm (Simeone et al. 1999). According to localfishermen, nets are set within 20-30 m depthif left at sea during the day and at deeperdepths of 60-70 m when left overnight. Thelatter situation is consistent with our data,where the bird remained at the respectivewater depths overnight. Furthermore, ac-cording to information provided by fisher-men (pers. comm. to A. S.), as fish and per-haps other marine animals get entangledover time, nets become progressively heavierand sink to greater depths which could ex-plain the slow, but continuous sinking of thenet after the study penguin became entan-gled. Finally, the frequent stops during haul-ing are typical as fishermen retrieve theirnets manually and need to stop several timesto rest. These pauses become shorter duringthe hauling operation as the net becomeslighter. Thus, we are confident that the pen-guin did indeed become entangled in a gillnet.

Incidental entanglement and drowningof penguins in this area has been previouslyreported in Puñihuil, where at least 50 Hum-boldt and Magellanic Penguins died duringsummer 2006 (Skewgar et al. 2009). Al-though high numbers of drowned birds arenot common, chronic entanglement of smallnumbers (such as the one reported here) iscommon in Puñihuil (Simeone, pers. obs.).

Incidental mortality of penguins hasbeen reported in trawl nets (Gandini et al.1999; Yorio and Caille 1999; Gonzáles-Zeval-los and Yorio 2006; Gonzáles-Zevallos et al.2007) and longlining gear (Nel et al. 2002;Moreno et al. 2006). Also, entanglement indiscarded fishing gear such as nets and nylonfishing lines poses a potential threat and isan occasional source of penguin mortality(Pütz, pers. obs.; Harrigan 1992). However,mortality associated with gill nets appearsmuch more common in Chile (Simeone et al.1999, Schlatter et al. 2009) and Peru (Majlufet al. 2002), but also elsewhere (Darby andDawson 2000), than previously anticipated.For example, in March 2009 a mass mortalityof nearly 1,380 Magellanic Penguins, bothadults (48%) and juveniles (52%), occurredin south-central Chile on a beach near

Figure 1. Diving activity of a Magellanic Penguin from Puhuil islets, southern Chile, drowned in a gill net: (a) entire dprofile, (b) onset of last dive and (c) end of last dive. Timigiven are local summer time (GMT-3).

124 WATERBIRDS

Queule (39°23’S, 73°13’W), about 300 km tothe north of the Puñihuil islets (Schlatter etal. 2009). Examination of carcasses revealedthat the most likely cause of death was as-phyxia due to drowning (Schlatter et al.2009), which was confirmed by several re-ports from fishermen. However, the real ex-tent of this mortality remains unknown andit can be assumed that many carcasses eithersank before being washed ashore or driftedelsewhere.

All these incidents imply that fishery-re-lated mortality may reach unacceptable lev-els not only for local, but also regional andeven global penguin populations (c.f. Majlufet al. 2002). Consequently, as in other fishingoperations, mitigation measures should bedeployed to decrease penguin and also oth-er seabird and marine mammal mortality as-sociated with artisanal fishing along the Chil-ean and Peruvian coasts (Majluf et al. 2002).In contrast to recent advances in mitigationmeasures for longline and trawler fishing,only a few studies have investigated potentialmeasures to reduce seabird bycatch in artisa-nal and gill net fishing (Bull 2007). However,the deployment of acoustic pingers and alsoan increase in the visibility of the net, for ex-ample by using metal oxide/barium sul-phate nets, have the potential to significantlyreduce seabird and marine mammal bycatch(Melvin et al. 1999; Trippel et al. 2003). Fur-ther, the establishment of marine protectedareas where human activities are regulatedin an appropriate manner without compro-mising either the survival of seabirds and ma-rine mammals or the economic viability oflocal fisheries (c.f. Boersma and Parrish1999) can reduce seabird bycatch. Such hasalready been proposed for Puñihuil to spe-cifically protect penguins (Skewgar et al.2009).

ACKNOWLEDGMENTS

Financial support derived from the Antarctic Re-search Trust. We are particularly grateful to “Ecoturis-mo Puñihuil” for organizing the trips to the islands andhelp with logistics, including lodging. Sphenisco e.V.helped making contacts at Puñihuil. CONAF (ChileanForest Service), through Hernán Rivera, provided per-mits to work at Puñihuil Islets and the Subsecretaría dePesca (Undersecretariat of Chilean Fisheries) provided

permits for handling penguins. The cooperation of theproject FONDAP-FONDECYT 1501-0001 is appreciat-ed. Thanks to L. Baxter for proofreading.

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