Ingestion of plastic marine debris by longnose lancetfish (Alepisaurus ferox) in the North Pacific Ocean

Ingestion of plastic marine debris by longnose lancetfish (Alepisaurus ferox)in the North Pacific Ocean

Lesley A. Jantz a,!, Carey L. Morishige b,c, Gregory L. Bruland d, Christopher A. Lepczyk e

a Pacific Islands Regional Observer Program, National Oceanic and Atmospheric Administration, 1601 Kapiolani Blvd., Suite 1110, Honolulu, HI 96817, USAb National Oceanic and Atmospheric Administration, Marine Debris Program, 1305 East West Highway, SSMC4 10th Floor, Silver Spring, MD 20910, USAc I.M. Systems Group, Inc., 3206 Tower Oaks Blvd., Suite 300, Rockville, MD 20852, USAd Biology Department, Principia College, 1 Maybeck Pl., Elsah, IL 62028, USAe Department of Natural Resources and Environmental Management, University of Hawai‘i at Manoa, 1910 East-West Road, Honolulu, HI 96822, USA

a r t i c l e i n f o

Keywords:Hawaii-based longline fisheryIngestionLongnose lancetfishMarine debrisPiscivorous fishPlastic

a b s t r a c t

Plastic marine debris affects species on most trophic levels, including pelagic fish. While plastic debrisingestion has been investigated in planktivorous fish in the North Pacific Ocean, little knowledge existson piscivorous fish. The objectives of this study were to determine the frequency of occurrence andthe composition of ingested plastic marine debris in longnose lancetfish (Alepisaurus ferox), a piscivorousfish species captured in the Hawaii-based pelagic longline fishery. Nearly a quarter (47 of 192) of A. feroxsampled contained plastic marine debris, primarily in the form of plastic fragments (51.9%). No relation-ship existed between size (silhouette area) or amount of plastic marine debris ingested and morphomet-rics of A. ferox. Although A. ferox are not consumed by humans, they are common prey for fishcommercially harvested for human consumption. Further research is needed to determine residence timeof ingested plastic marine debris and behavior of toxins associated with plastic debris.

Published by Elsevier Ltd.

1. Introduction

Pollution by plastic marine debris constitutes a major threat tomarine life (Derraik, 2002). Ingestion of plastic marine debris byseabirds, turtles, and marine mammals is well acknowledged andrecognized as a serious hazard (Andrady, 2011; Azzarello andVan Vleet, 1987; Derraik, 2002; Laist, 1997; Mallory, 2008; Moore,2008; Teuten et al., 2009; Tomas et al., 2002). However, less isknown about the ingestion of plastic marine debris by piscivorousmarine fishes (Carpenter et al., 1972; Hoss and Settle, 1990; Kartaret al., 1973; Possatto et al., 2011).

Observations made incidental to other studies indicate thatmarine fish do ingest plastic marine debris (Hoss and Settle,1990). For example, in a food habit study of longnose lancetfish(Alepisaurus ferox) by Kubota and Uyeno (1970), 78 pieces of plasticand rubber were found in the stomach contents of 36 specimens.Jackson et al. (2000) studied the diet of the southern opah and dis-covered a high occurrence, 14% of the total stomachs analyzed, ofplastic debris with a maximum size of 67.5 cm. In a comparativefood study of yellowfin tuna (Thunnus albacares) and blackfin tuna(Thunnus atlanticus), Manooch and Mason (1983) found a 31.6%

frequency of non-food items (plants, feathers, globs of tar and plas-tics) in the stomachs of yellowfin tuna compared to 15.7% in black-fin tuna. Hoss and Settle (1990) also found that during laboratoryexperiments fishes in early life stages feed on polystyrene micro-spheres sorted to appropriate food particle size (100–500 lm).The first to report fish feeding on plastic marine debris wasCarpenter et al. (1972) who found eight out of 14 species of fishcollected in a plankton tow in the coastal waters of New Englandto contain plastic debris ranging in size from 0.1 to 2 mm. Kartaret al. (1973) observed plastic debris ingested by juvenile flounderin the Severn Estuary in Great Britain, while Colton et al. (1974)found no plastic debris in the gut contents of over 500 larval andjuvenile fishes in the northwestern Atlantic. Early documentationof the ingestion of plastic by piscivorous marine fishes focused pri-marily on the larval and juvenile stages (Hoss and Settle, 1990). Amore recent study on the ingestion of plastic marine debris exam-ined the juvenile, sub-adult, and adult phases of three marine cat-fish species in a tropical estuary in Northeast Brazil (Possatto et al.,2011).

In the North Pacific Ocean, the Subtropical Convergence Zone(STCZ) is a known area of marine debris concentration (Kubota,1994; Pichel et al., 2007; Maximenko et al., 2012). The STCZ is a re-gion of surface layer convergence caused by wind fields and associ-ated Ekman transports that concentrate marine debris and floatingplankton (Howell et al., 2012; Kubota, 1994; Pichel et al., 2007).Due to the increased biological productivity in the STCZ, it hasbecome a significant forage and migration corridor for species such

0025-326X/$ - see front matter Published by Elsevier Ltd.http://dx.doi.org/10.1016/j.marpolbul.2013.01.019

! Corresponding author. Tel.: +1 808 944 2253; fax: +1 808 973 2934.E-mail addresses: [email protected] (L.A. Jantz), [email protected]

(C.L. Morishige), [email protected] (G.L. Bruland), [email protected](C.A. Lepczyk).

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as the albacore tuna (Polovina et al., 2001) and loggerhead sea turtles(Howell et al., 2010, 2008; Polovina et al., 2004). The shoaling of thethermocline in this region is believed to attract swordfish (Xiphiasgladius) close to the surface, and as a result, is a region targeted bythe Hawaii-based shallow-set longline fishery (Seki et al., 2002).

The Hawaii-based shallow-set longline fishery effort is distrib-uted north of the Hawaiian Archipelago, generally centered onthe North Pacific Subtropical Frontal Zone, in close proximity tothe STCZ, where multiple fronts and surface convergence are evi-dent, most prominently at 32!–34!N and at 28!–30!N (Seki et al.,2002). The typical shallow-set fishing season peaks in the winterand continues into the early spring, although some vessels will fishthroughout the summer months.

While considered a discard in the Hawaii-based longline fish-ery, A. ferox are a voracious, widely distributed, dielly migratingmesopelagic fish caught throughout the water column by commer-cial pelagic longline gear. They inhabit mainly tropical and sub-tropical waters (Orlov and Ul’chenko, 2002). A. ferox are ambushpredators and common prey items found in their stomachs areslow swimming species and passive drifters (Romanov andZamorov, 2002). The wide variation of sizes, textures, colors, andshapes of stomach contents demonstrate the opportunistic feedingbehavior and lack of selectivity (Kubota and Uyeno, 1970).Stomach contents of A. ferox are generally well-preserved becausefood is stored in the stomach and digested in the intestines (Allain,2003; Potier et al., 2007).

This study evaluated the ingestion of plastic marine debris by apiscivorous ambush predator, A. ferox, with the goal of quantifyingthe amount and type of plastic marine debris ingested. The objec-tives of this paper are twofold: to determine the frequency ofoccurrence and composition of ingested plastic marine debrisand to compare A. ferox morphometrics to the size (silhouette area)of ingested debris.

2. Materials and methods

2.1. Specimen collection and analysis

Fishery observers from the National Oceanic and AtmosphericAdministration (NOAA) Pacific Islands Regional Observer Pro-gram (PIROP) collected A. ferox, a common bycatch species,aboard commercial vessels departing in November 2010 throughAugust 2011. The fish were collected in longline fishing grounds,centered on the North Pacific Subtropical Frontal Zone. A total of192 A. ferox were collected from 41 trips from the Hawaii-basedshallow-set longline fishery by 28 unique fishery observers(Fig. 1). To ensure ease of collection for the observers and fisher-men, the current PIROP systematic sampling protocol (NOAAPIROP Field Manual, 2011) of measuring every third fish speciescaptured on the longline was followed. Fishery observers col-lected the third fish if it was an A. ferox, measured the forklength (FL) in centimeters, and stored the fish in the vessel’sfreezer or ice hold.

A. ferox, after thawing in the lab, were weighed to the nearest kg(wet weight). For each fish, a superficial straight-line cut from theanus anterior through the mid-pelvic girdle was performed to ex-pose the peritoneal cavity. Stomachs were then extracted wholewith incisions at the cardiac and pyloric sphincters. Stomachs wereweighed (wet weight) to the nearest gram and contents were re-moved and processed similar to Jackson et al. (2000). Fish werenot sorted by sex because A. ferox are synchronous hermaphro-dites, where the ovarian and testicular tissues are simultaneouslydeveloped (Smith and Atz, 1973).

Plastic marine debris pieces <1 mm in size were not quantifiedin this study as they were difficult to see with the naked eye. Preyitems and plastic marine debris were analyzed when plastic waspresent in the stomach contents. Stomachs of fish with prey that

Fig. 1. The distribution of A. ferox samples collected from Hawaii-based shallow-set trips from November 2010 to August 2011.

98 L.A. Jantz et al. / Marine Pollution Bulletin 69 (2013) 97–104

did not have any detectable (with the naked eye; >1 mm) plasticmarine debris were not analyzed.

2.2. Plastic characterization

Each piece of plastic marine debris was measured and catego-rized by physical characteristics such as type, shape, malleability,and color. The six-category system of classification included: net,rope, fragment, strap, plastic bag, and miscellaneous (Fig. 2a). Thisclassification was informed by current literature that has describedingested plastic marine debris as fragments, film, fishing line, rope,nylon rope, bottle, packaging, plastic bag and hard plastic (Boergeret al., 2010; Davison and Asch, 2011; Jackson et al., 2000; Manoochand Mason, 1983; Possatto et al., 2011).

The criteria used to subcategorize the net category was based onwhether the plastic marine debris was single or multi-strand mono-filament or systematically woven or knotted (Fig. 2b). Plastic marinedebris that resembled net, but was not made of monofilament orsystematically woven or knotted, was considered to be rope. Therope category was divided into two subcategories, braided and mis-

cellaneous (Fig. 2c). The pliability of each fragment was determinedby touch. If the fragment bent without breaking, it was consideredsoft, if it broke it was considered hard. If the debris had any obviouscurvature in shape, it was considered to be rounded (Fig. 2d). Theplastic marine debris was also divided into nine color categories:black, blue, brown, clear, gray, green, green and white, orange,and white.

Each piece of plastic marine debris was dried and if flexible,straightened out before measurement. Weight (g) was measuredusing an analytical scale whereas vernier calipers were used tomeasure thickness (mm) and maximum length (mm). Silhouettearea of the plastic debris was measured (mm2) using Image J photoanalysis software. The total and percent silhouette area, weightand length, in addition to the mean with standard deviation, werecalculated for each plastic marine debris category.

2.3. Statistical analyses

All statistical analyses were performed using SigmaStat (Ver-sion 3.5, Systat Software, San Jose, CA). A linear regression was

Fig. 2a. The six main categories of plastic marine debris collected from the stomach contents of A. ferox captured in the shallow-set longline fishery are: (a) rope, (b) net, (c)strap, (d) plastic bag, (e) fragment, and (f) miscellaneous.

L.A. Jantz et al. / Marine Pollution Bulletin 69 (2013) 97–104 99

used to compare the length and weight of A. ferox. A plus four con-fidence interval for a single proportion (a = 0.05), a common anal-ysis for confidence intervals of small sample sizes (Moore et al.,2009), was used to calculate the confidence interval for the propor-tion of fish that ingested plastic marine debris.

3. Results

3.1. Presence of plastic marine debris

This study found plastic marine debris present in the stomachcontents of A. ferox. Plastic marine debris was found inside 24.5%(47 of 192) of the stomachs of collected fish specimens. The 95%confidence interval calculated 19–31% of A. ferox caught in the Ha-waii-based shallow-set longline fishery to contain ingested plasticmarine debris.

3.2. Size of plastic marine debris

The mean total silhouette area of ingested debris (Fig. 3a), mea-sured by Image J to the nearest 0.1 mm was 3,794.4 mm2 (SD12,361.9 mm; range 27.8–68,983.5 mm2). The outliers corre-sponded to three different A. ferox that ingested: (1) plastic frag-ments and a piece of net with a total silhouette area of14,373.9 mm2, (2) a large piece of a black plastic bag (Fig. 3a) witha total silhouette area of 50,983.1 mm2, and (3) a braided rope andpiece of net with a total silhouette area of 69,439.6 mm2. The meantotal weight (Fig. 3b) and total length (Fig. 3c) of plastic marinedebris ingested per fish was 1.2 g (SD 1.7 g; range 0.02–9.98 g)and 166.2 mm (SD 188.4 mm; range 5.1–876.9 mm), respectively.The total length outlier, at 800 mm, was the same outlier for the to-tal silhouette area and total weight distribution—one fish that in-gested a braided rope and piece of net.

3.3. Types and colors of plastic marine debris

The ingested plastic marine debris appears to come from avariety of sources for which the country of origin and sourcecould not be determined. Plastic fragments comprised 51.9% (mean28.5 pieces, SD 16.3 pieces; range 1–56 pieces) of the plasticmarine debris categorized, followed by rope with 21.3% (mean12.0, SD 6.8; range 1–23) and net 20.4% (mean 8.9, SD 5.9; range1–19). Strap, plastic bag, and the miscellaneous categoriestotaled <8%.

Although there were only two pieces in the plastic bag cate-gory, they accounted for 28.8% of the total silhouette area. Themean silhouette area was 25,921.0 mm2 (SD 25,061.2 mm2;range 860–50,983 mm2) (Table 1). Fragments had the largest per-centage of total weight, 42.7% with a mean weight of 0.4 g (SD0.1 g; range 0–3.0 g) (Table 2). The rope category (n = 16) repre-sented the largest percentage of total length, 35.0%, with a meanlength of 121.6 mm (SD 29.5 mm; range 3–660 mm) (Table 3).The fragment and net categories were further divided into sub-categories with associated totals, percentages and means(Table 4).

3.4. Comparison of A. ferox morphometrics with size of plastic marinedebris

A. ferox collected in this study varied considerably in lengthranging from 48 to 146 cm FL. The length distribution of fish withingested plastic marine debris ranged from 65 to 137 cm FL.(Fig. 4). Both distributions are bi-modal with peaks at the 80 cmand 130 cm FL measurements. There were few fish sampled smal-ler than 60 cm or larger than 140 cm. There were no significantrelationships detected between FL and the silhouette area of theingested plastic marine debris.

Fig. 2b. The subcategories for plastic net debris collected from the stomach contents of A. ferox captured in the shallow-set longline fishery are: (g) multi-strand monofilament,(h) single strand monofilament, (i) multi-filament, and (j) miscellaneous.

100 L.A. Jantz et al. / Marine Pollution Bulletin 69 (2013) 97–104

3.5. Identified ingested prey

Stomach content analysis revealed that 24.8% (36 of 145) of A.ferox stomachs were empty and 75.1% (109 of 145) contained preyitems, but no plastic. Of the A. ferox stomachs in which plastic waspresent, 68.1% (32 of 47) were a mix of plastic marine debris andprey items while 31.9% (15 of 32) of the stomachs contained sim-ply plastic. The prey collected and identified were diverse and indi-cate the different depths of feeding for A. ferox (Table 5). Themajority of the prey collected were pelagic and epipelagic organ-isms (78%) followed by mesopelagic organisms (21%). There werea few non-vertically migrant species from mesopelagic depths,such as the hatchetfish (family Sternoptychidae), as well as evi-dence of cannibalism. The buoyancy of plastic debris discoveredin the lancetfish stomachs was not measured and thus depth ofplastic debris ingestion could not be postulated.

4. Discussion

Findings of this study confirm ingestion of plastic marine debrisby A. ferox with 24.5% (47 of 192) of collected specimens with vis-ible plastic marine debris found in the stomach. The number of fishin this study found to have ingested plastic marine debris is likely aconservative estimate as plastic marine debris may have beenpresent in the intestines (not dissected) or missed during visualinspection (too small to see with naked eye). This study adds tothe growing base of knowledge on the ingestion of plastic marinedebris by piscivorous fish.

The majority of the plastic marine debris found in this studywas macro-debris (mean length = 73.9 ± 111.1 mm). Plastic marinedebris measured in this study more closely resembled the size ofplastic found in the dietary study of the southern opah (Jacksonet al., 2000) in which a high incidence of plastic marine debris

Fig. 2c. The subcategories for plastic rope debris collected from the stomachs of A. ferox captured in the shallow-set fishery are: (k) braided, and (l) miscellaneous.

Fig. 2d. The subcategories for plastic fragment debris collected from the stomachs of A. ferox captured in the shallow-set longline fishery are: (m) hard, (n) soft, (o) rounded,and (p) hollow square pattern.

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0

5

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15

20

25

30

1500 3000 6000 12000 24000 48000 96000

No.

of l

ongn

ose

lanc

etfi

sh

Total area (mm2) of plastic marine debris ingested per fish3,794.4 mm2 mean, 12,361.9 mm2 SD

05

10152025303540

1 2 3 4 5 6 7 8 9

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ongn

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sh

Total weight (g) of plastic marine debris ingested per fish1.2 g mean, 1.7g SD

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100 200 300 400 500 600 700 800

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ongn

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Total length (mm) of plastic marine debris ingested per fish166.2 mm mean, 188.4 mm SD

A

B

C

D

Fig. 3. Distribution of the (A) total silhouette area (mm2), (C) total weight (g), and (D) total length (mm) of plastic marine debris ingested by each of the 47 A. ferox captured inthe shallow-set longline fishery. The picture insert (B) is a plastic bag, the largest area outlier. The star represents the opening of the fish’s stomach.

Table 1Silhouette area (mm2) and classification of plastic marine debris from the stomach contents of the 47 A. ferox captured in the shallow-set longline fishery.

Debris N (%) Area (mm2) Area (%) Mean area ± 1 SD Range (mm2)

Fragment 38.0 (47.5) 24,929.90 13.9 445.2 ± 464.9 (33.3–2,130.9)Rope 16.0 (20.0) 7019.60 3.9 305.2 ± 433.7 (27.8–2,086.5)Net 19.0 (23.8) 93,413.00 51.9 4202.7 ± 14,752.9 (39.4–68,983.5)Strap 4.0 (5.0) 1644.30 0.5 411.1 ± 142.6 (281.1–610.1)Plastic bag 2.0 (2.5) 51,843.70 28.8 25,921.0 ± 35,442.0 (860.6–50,983.1)Miscellaneous 1.0 (1.3) 954.5 0.9 954.5 ± 0.0 !954.5Total 80.0 (100) 179,804.90 – 32,239.7 ± 51,236.1 (33.3–68,983.5)

Table 2Weight (g) and classification of plastic marine debris from the stomach contents of the 47 A. ferox captured in the shallow-set longline fishery.

Debris N (%) Weight (g) Weight (%) Mean weight ± 1 SD Range (g)

Fragment 38 (47.5) 23.6 42.7 0.4 ± .59 (0.0–3.0)Rope 16 (20.0) 7.7 13.9 0.3 ± .90 (0.0–4.3)Net 19 (23.8) 19.2 34.6 0.9 ± 2.10 (0.0–9.3)Strap 4 (5.0) 1.9 3.4 0.1 ± .050 (0.0–0.1)Plastic bag 2 (2.5) 2.6 4.6 1.3 ± 1.78 (0.0–2.5)Miscellaneous 1 (1.3) 0.4 0.7 1.9 ± 0.0 1.88Total 80 (100) 55.4 – 4.9 ± 5.42 (0–9.3)

Table 3Length (mm) and classification of plastic marine debris from the stomach contents of the 47 A. ferox captured in the shallow-set longline fishery.

Debris N (%) Length Length (%) Mean length ± SD Range (mm)

Fragment 38.0 (47.5) 1816.2 22.8 32.4 ± 25.0 (5.1–138.9)Rope 16.0 (20.0) 2797.1 35 121.6 ± 131.9 (3.1–660.4)Net 19.0 (23.8) 2386.3 29.9 108.5 ± 152.5 (11.4–723.9)Strap 4.0 (5.0) 105 1.3 69.1 ± 15.1 (51.3–83.9)Plastic bag 2.0 (2.5) 600.4 7.5 300.2 ± 367.4 (40.4–560.0)Miscellaneous 1.0 (1.3) 276.2 3.5 105 ± 0.0 !105Total 80.0 (100) 7981.1 – 736.8 ± 691.9 (3.1–723.9)

102 L.A. Jantz et al. / Marine Pollution Bulletin 69 (2013) 97–104

was documented (67.5 cm maximum). The southern opah and A.ferox are comparable in length and appear to feed on similar prey.In addition, the type of marine debris collected in the southernopah study (mono-filament line, strap of plastic) resembled someof the marine debris collected from A. ferox stomach contents.

No relationship between fish length and weight to plastic debrisload was found. This lack of a relationship was unexpected as itwas postulated that the larger a fish becomes, the larger the preyitems they are able to and thus may consume. No studies to datehave looked at the length and weight of fish compared to ingestedplastic marine debris.

Natural prey collected from stomach contents of fish with andwithout plastic marine debris was similar, corresponding to preyfound in Allain (2003) and Kubota and Uyeno (1970) diet studiesof A. ferox. Therefore, there appeared to be no differences in feedingbehavior between fish that ingested plastic marine debris and fishthat ingested only natural prey. Prey identified and collected in thisstudy were primarily epipelagic and mesopelagic species with afew non-vertically migrant mesopelagic species, such as the ang-lerfish (Ceratioid suborder) (Pietsch, 2009) and the hatchetfish(Sternoptyx pseudobscura). Allain (2003) found Sternoptyx sp. inan A. ferox dietary study, which demonstrates that A. ferox can diveto mesopelagic depths, 200–1000 m below the ocean surface.According to Kubota and Uyeno (1970), longnose lancetfish under-take vertical migration and feed on organisms found in the epi-,meso-, and bathypelagic zones in the ocean. A. ferox have the ten-dency to feed on slow-moving, less muscular, gelatinous speciesthroughout a wide range in the water column (Moteki et al.,2001). Although there is no link in this study to directly associatethe plastic marine debris ingested by A. ferox with the ocean depthsof associated prey, such as the non-vertically migrant hatchetfishand anglerfish, there may be potential to bridge the gap betweenplastic marine ingestion and ocean depth in future studies. Analy-

sis of non-vertically migrant species in the mesopelagic depths,targeted with longline gear or a deep-water trawl, may revealthe potential of plastic marine debris to move vertically through-out the water column. While A. ferox may not be the optimal testfish species due to regional variations in its tropical and subtropicaldistribution and its method of predation, it plays an important rolein oceanic food webs and serves as common prey for tunas, mar-lins, sharks, opahs and other predatory fish (Orlov and Ul’chenko,2002) that are commercially harvested for human consumption.

In this study, A. ferox were collected in close proximity to theSTCZ, a known area of marine debris aggregation, consequently,these results cannot be extrapolated to A. ferox in all tropical andsubtropical regions. Previous studies of plastic debris ingestionby planktivorous fishes in the North Pacific Ocean in the area ofthe STCZ, found 35.0% of fishes (Families Myctophidae, Scombere-socidae, and Stomiidae) to have ingested plastic marine debris(Boerger et al., 2010). Meanwhile, Davison and Asch (2011), mini-mizing net feeding bias, found 9.2% of fishes (Families Sternopty-chidae, Stomiidae, and Myctophidae) to have ingested plasticmarine debris in the area of the STCZ.

This study found nearly 25% of A. ferox captured in the North Pa-cific Ocean in the area of the STCZ had ingested various types, col-ors, and sizes of plastic marine debris. The 95% confidence intervalcalculated 19–31% of A. ferox caught in the Hawaii-based shallow-set longline fishery to contain ingested plastic marine debris. Thisstudy adds to the body of knowledge on piscivorous fish ingestionof marine debris. Further research is needed to determine resi-dence time of ingested plastic marine debris and behavior of toxinsassociated with plastic debris.

Acknowledgements

We thank the fishery observers in the Pacific Islands RegionalObserver Program who collected the A. ferox examined in thisstudy, and without whom this project would not have beenpossible. Special thanks to B. Humphreys, NOAA Fisheries, for the

Table 4Totals of fragment and net subcategories of plastic marine debris from the stomachcontents of the 47 A. ferox captured in the shallow-set longline fishery.

Fragment and net marine debris N Mean ± SD Range

Hard fragment 38 19.5 ± 11.1 1.0–38.0Soft fragment 11 6.0 ± 3.3 1.0–11.0Rounded fragment 5 3.0 ± 1.6 1.0–5.0Hollow square pattern fragment 2 1.5 ± 0.7 1.0–2.0Muli-strand monofilament net 12 6.5 ± 3.6 1.0–12.0Single-strand monofilament net 5 3.0 ± 1.6 1.0–5.0Multifilament net 2 1.5 ± 0.7 1.0–2.0Miscellaneous net 3 2.0 ± 1.0 1.0–3.0Total 78 43.0 ± 23.6 1.0–50.0

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NO PLASTICPLASTIC INGESTION

Fig. 4. Histogram of FL measurements of all A. ferox sampled. The dark colored barsrepresent fish with no ingested plastic marine debris. Light colored bars representfish with ingested plastic marine debris.

Table 5Prey items collected from stomach contents of 32 of the 47 A. ferox with ingestedplastic marine debris. Type: P (pelagic) = fish living without relation with bottom, E(epipelagic) = ocean surface-200 m, M (mesopelagic) = 200–1000 m, B (bathype-lagic) = 1000–4000 m. j = juvenile, a = adult (Clark, 1974; Allain, 2003; Pietsch, 2009).

Family or species, common name Type Number Percentof totalprey (%)

FishesAlepisaurus ferox, longnose lancetfish E, P, M 7 2.60Anoplogastridae, fangtooths jE, M, B – aM, B 35 12.90Pteraclis aesticola, fanfish E 1 0.40Ostraciidae, boxfishes jE – aD 11 4.10Ranzania laevis, slender mola E, M 3 1.10Phosichthyidae, lightfishes E, M 3 1.10Sternoptychidae, hatchetfish M 10 3.70Trachipteridae, ribbonfishes M 1 0.40Ceratioid (suborder), anglerfishes M, B 1 0.40

Unidentified fisha 5 1.80

CrustaceansHyperiidae, amphipods E 182 67.20Phronimidae, amphipod E 1 0.40

CephalopodsOnychoteuthidae, hooked squid P 2 0.70Histioteuthidae, squid M 5 1.80Enoploteuthidae, squid M 4 1.50Total 271 100

a Unidentified fish represents pieces of prey that were digested beyondidentification.

L.A. Jantz et al. / Marine Pollution Bulletin 69 (2013) 97–104 103

generous use of his lab and freezers, Dr. E. Howell, NOAA Fisheries,for his assistance in providing oceanographic information and C.Arthur, NOAA Marine Debris Program, for her expertise in plasticmarine debris and manuscript review. We also thank D. Hawnand B. Mundy of NOAA Fisheries, for their guidance and help inidentifying prey items found in stomach contents and the anony-mous reviewers for their helpful comments regarding this manu-script. We appreciate Dr. A. Taylor from the Department ofZoology at the University of Hawai‘i at Manoa, for his statisticalassistance and A. Choy, a Ph.D. candidate in the Department ofOceanography at the University of Hawai‘i at Manoa, for her exper-tise in stomach sampling.

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