Increasing lifting-bag mesh size to reduce codend occlusion in Australian whiting (Sillago spp.) trawls

Some small-meshed fish-trawl codends require so-called “protective,” “strengthening,” or “lifting” bags for structural support, but these can occlude mesh openings and reduce size/species selectivity. This study compared two lifting-bag mesh sizes (94 and 216 mm stretched mesh opening; SMO) surrounding a 46-mm SMO codend in an Australian whiting-trawl fishery. During 37 deployments off Newcastle, New South Wales, compared to the 94-mm lifting bag, the 216-mm lifting bag significantly reduced the catches of juvenile eastern school whiting (Sillago flindersi <17 cm total length; TL) by ~35% and small unwanted velvet leatherjacket (Meuschenia scaber) by ~67%. Total bycatch declined by ~50%. However, ~6% of eastern school whiting ≥17 cm TL also escaped, along with some important byproduct species. Relative size–frequency analysis revealed no significant TL effects for eastern school whiting although there was evidence of fewer individuals being retained with the larger-meshed lifting bag. The data reiterate species-specific lifting-bag effects and the importance of evaluating both conservation benefits and economic impacts when subtly modifying trawl configurations.

1 Introduction

Benthic fish trawls are one of the most common active fishing gears used globally but are also among the least selective, typically associated with 25% discarded catches (1). All components of fish trawls cumulatively affect their selectivity, although lateral mesh openings in the codend (where the catch accumulates) ultimately dictate what is retained or escapes (2). Consequently, in many fish-trawl fisheries, minimum codend stretched mesh openings (SMOs) are mandated to control size selection, and typically for the smallest targeted species (2).

Beyond SMO, there are various other often regulated and unregulated technical factors that affect the selectivity of codends (2). Common parameters include mesh orientation (3, 4), twine material (5), diameter [Ø, (6)], circumference (7, 8), short lastridge ropes (9), and attachments designed to either restrict openings (10), prevent wear (11), and/or increase strength (12–14).

Among the latter are attachments surrounding the entire codend, typically made from meshes at least twice the SMO and commonly termed “lifting” (15), “strengthening” (16), or “protective” (12) bags. Such modifications are sometimes required in fisheries where the codend SMOs are small (e.g., < 50 mm) and the twine Øs are proportionally narrow and not strong enough to hold catches during retrieval (6). Although correctly configured lifting bags (i.e., to the same circumference as codends) may not restrict lateral openings, they can cover (or occlude or “mask”) some meshes and so affect fish escaping (2). Nevertheless, the influences of lifting bags are species- and configuration-specific, ranging from no effects (12) to significant and substantial reductions in size selection (17).

One Australian fishery where lifting bags are routinely used, but have not been assessed for influences on codend selectivity, is the Queensland finfish (stout whiting, Sillago robusta) fishery, involving boat seines and otter trawls fishing inshore (~20–90 m) between 24.7 and 28.2°S. Codend SMOs are ~36–40 mm, made from ~2 mm Ø twine and typically surrounded by lifting bags at least 3 m long and comprising SMOs of at least 90 mm (4 mm twine Ø). No data are available on the appropriateness of this lifting-bag SMO in trawls, or if any increase might improve size selectivity.

Recently, in response to individual transferable quota being introduced for combined catches of S. robusta and its congeneric, eastern school whiting, S. flindersi in the adjacent state of New South Wales (NSW; between 30.8 and 33.5°S), some fishers have Trialled similar configurations of codends used in Queensland and more specifically ~45 mm SMO in boat seines and trawls to target whiting ≥17 cm total length [TL; (15, 18, 19)]. Broadhurst (20) showed that increasing the lifting-bag mesh size to 216 mm improved the selection of 45-mm boat-seine codends for stout whiting, but no work is available describing the impacts to fish trawls. This study aimed to address the stated deficit by comparing two lifting bags made from regionally available mesh sizes (94 and 216 mm) while maintaining codend mesh size (46 mm) and twine Øs between configurations.

2 Methods

The work was done during eight nights in February and March 2025 using a volunteer vessel (FV Edward James) targeting whiting (22–75 m) off Newcastle, NSW (32.9°S; 151.8°E). The vessel towed a single, two-seam trawl (55 m headline and nominal 90 mm SMO throughout) constructed from polyethylene (PE) netting attached to 175 m sweeps and spread by steel V otter boards. Initially, the posterior trawl body was attached directly to the codend, but after four nights an intermediatory lengthener section (~46 mm SMO and 300 transverse (T) meshes × 199 normal (N) meshes) was installed to better facilitate codend retrieval (Figure 1A). The posterior trawl and then the lengthener were selvedged to facilitate attaching the two identical codends with different lifting bags via a 5 m length of rope.

Figure 1

Figure 1. Schematic diagrams of the (A) posterior trawl and lengthener, (B) 46-mm codend, and (C) 94- and (D) 216-mm lifting bags. SMO, stretched mesh opening; T, transversal meshes; N, normal meshes; B, bars; Ø, diameter; and PE, polyethylene.

Both codends and lifting bags were made from green PE netting with braided twine; panels of which were measured for 20–40 replicates of SMOs (nearest 0.5 mm) and twine Ø (nearest 0.1 mm) using a legislated gauge and Vernier calipers. Each codend measured 225 T × 100 N and comprised 45.9 ± 0.1 mm SMO and 2.0 ± 0.0 mm Ø twine for a total twine area of ~4.3 m² (Figure 1B). Six-mm Ø Dyneema^® lastridge ropes were attached along the sides (1:1 with SMO). Both lifting bags had the same stretched lengths (~3.5 m), circumferences (~9.3 m), and twine Øs (4.5 ± 0.1 and 4.6 ± 0.0 mm), but comprised either 93.8 ± 0.3 mm or 216.1 ± 0.6 SMO (and were distinguished as such), with twine areas of 3.1 and 1.4 m² (Figures 1C, D).

At the start of each night, one of the codend/lifting bags was attached to the trawl/lengthener and fished during up to three replicate deployments (50.0–107.6 min) before being alternated with the second configuration which was similarly deployed (all between 18:20 and 06:20 h). Technical data collected included the deployment duration (min; time between otter boards on and off the seabed), speed over the ground (SOG; ms⁻¹) and average fishing depth (m) (the latter using Lowrance electronics).

At the end of each deployment, the codend was brought onboard and the total catch volume estimated based on the length and diameter of the contents before being emptied into a water-filled hopper [following Broadhurst (20)]. All whiting were removed and retained, with subsamples (~50 kg) separated by species and used to partition total catch. Subsamples of up to 170 individuals deployment⁻¹ were measured for TL (nearest 0.5 cm). Catches of all other retained species were individually weighed and counted. The remaining total bycatch was estimated by separating from the retained and total, and a subsample (e.g., up to two 55-l boxes) was sorted. All subsamples were raised by scaling factors to the total numbers and weights onboard the vessel, producing continuous extrapolated estimates (rather than discrete counts). Excluding sizes, the raw subsample data were not systematically retained, precluding retrospective analyses of the original count data.

2.1 Statistical analyses

The SOG, deployment duration, and fishing depth were analysed raw using linear mixed models (LMM) comprising ‘lifting bag' as fixed and ‘nights' fished as a random effect. Catches for those species caught across most deployments were standardised (1 h⁻¹ trawled), log-transformed, and analysed using the same LMMs, but with depth and its quadratic form included as covariates (owing to a range of fished depths; see Section 3 Results). Models were fitted using the ASReml function in R (21) and inspected using QQ and residual plots, while statistical significance was evaluated at the 5% level using Wald F-tests (22).

Relative selectivity curves were fitted to the TL frequencies of eastern school whiting using generalised additive modeling (GAM) within the SELECT package in R (23, 24). Data were first scaled by subsampling fractions to estimate total frequencies deployment⁻¹. Relative selectivity curves encompassed the proportions at sizes (catch share) retained in the codend with the 216-mm lifting bag based on the combined catches with those in the codend with the 94-mm lifting bag via cubic regression splines (25). Fitted-spline confidence intervals were obtained using a 1,000 iteration double bootstrap (26), while a permutation test was used (1,000 resamples) to test for no TL effects due to lifting bag (27). The permutation test was blocked by day to control for temporal and environmental variation, including depth differences among days.

3 Results

In total, 21 and 16 deployments with the 94- and 216-mm lifting bags were completed during eight nights across similar deployment durations (1.8 ± 0.1 h) and SOGs (1.5 ± 0.0 ms⁻¹) (LMM, p > 0.05). The fished depths (26.1–67.7 m) were similar between treatments during most nights, but means were slightly different overall (45.4 ± 1.7 vs. 37.1 ± 1.9 m; LMM, p < 0.01) necessitating depth and its quadratic in the catch LMMs.

The total catch was 39.9 t; of which 18.6 t (mostly whiting) was retained and 21.2 t (or 53.1%) discarded (Table 1; Figure 2A). More than 63 species were recorded, although eastern school whiting (all retained) and yellowtail scad, Trachurus novaezelandiae (all discarded), dominated all catches (37.1 and 24.2%, respectively; Table 1). These two species along with 11 others (excluding stout whiting which were only caught in few deployments) formed the basis of catch analyses (Tables 1, 2).

Table 1

Table 1. List of species (common and Latin names) caught in descending total weights and their numbers and % weights (wt) discarded during 37 deployments of a fish trawl attached to 46-mm [stretched mesh opening (SMO)] codends with either of two lifting bags (94 and 216 mm SMO; see Figure 1) off Newcastle, New South Wales, Australia, during February and March 2025.

Figure 2

Figure 2. Differences in mean (+SE) weights 1-h⁻¹ trawled between codends with two different lifting bags (94- and 216-mm) for the weights of (A) total catches and (B) eastern school whiting, Sillago flindersi, and (C) relative size–frequency distributions for the latter (dashed line, n = 5,109 measured), with the proportions (black circles) and fitted splines (solid curve with shaded 95% confidence intervals) for the share of scaled-up catches for each total length (over both treatments) that were retained in the codend with the 216-mm lifting bag. **p < 0.01; ***p < 0.001.

Table 2

Table 2. Summaries of significance from Wald F-tests assessing the importance of lifting-bag mesh size on catches and the means (±SE) 1 h deployment⁻¹.

The LMMs revealed that compared to the 94-mm lifting bag, the 216-mm lifting bag facilitated the escape of significantly more juvenile eastern school whiting (< 17 cm TL by 34.4 and 35.5% for numbers and weights) and unwanted velvet leatherjacket, Meuschenia scaber (66.7% by weight) from the codend (LMM, p < 0.05; Table 2, Figure 2B). Several other small unwanted species, including gurnard, Chelidonichthys and Lepidotrigla spp., and red bullseye, Priacanthus macracanthus also had lower (non-significant) mean catches in the codend with the larger-meshed lifting bag which contributed to significant reductions in the total number and weight of bycatch (by 58.3 and 54.9%, LMM p < 0.05; Table 2, Figure 2A). However, the number of eastern school whiting ≥17 cm TL and the number and weight of retained octopus, Octopus spp. were also significantly lower (by 4.7, 41.8, and 41.3%, respectively, LMM, p < 0.05) and there were non-significant mean reductions in the numbers and weights of retained squid, Loligo spp. (37.7% and 36.9%) and goatfish, Upeneus spp. (32.5% and 38.7%) (p > 0.05; Table 2). Catches of species with individuals mostly larger than the codend SMO, including longspine flathead, Platycephalus longispinis, bluespotted flathead, P. caeruleopunctatus, and Balmain bugs, Ibacus peronii, remained similar (albeit variable) regardless of lifting-bag mesh size (LMM, p > 0.05; Table 2).

Eastern school whiting were caught across a narrow size range (mostly 18–24 cm TL) and in sufficient numbers to converge a GAM (Figure 2C). There were no significant TL effects, although the spline showed a slightly lower catch share of the smallest fish in the codend with the 216-mm lifting bag (permutation test, p > 0.05; Figure 2C).

4 Discussion

The data here contribute to those collected during one previous regional study comparing the same two lifting-bag mesh sizes in Scottish seines (20) and the few international studies assessing trawl lifting-bag effects; most of which have compared presence vs. absence (12, 14, 17) or circumference (13), rather than different mesh sizes. Like this previous work, there were species-specific effects that appear to have been driven by morphology and relative sizes, which ultimately will help to inform appropriate future configurations. However, prior to this discussion, some methodological constraints warrant consideration.

First, trawling for whiting in NSW occurs both diurnally and nocturnally (8, 19). However, the data here were restricted to nocturnal deployments, simply because this was when most fish were being targeted by the volunteer trawler during the sampled months. There may be species-specific differences in escape responses for the key species, with greater visibilities of the codend and lifting bag meshes during the day (28). For example, during diurnally deployed boat seines, Broadhurst (20) showed a similar increase in the escape of small stout whiting from the 216-mm lifting bag, but not eastern school whiting. While there are considerable differences between seines and trawls in terms of their deployment and fishing and especially SOGs (i.e., 0.3 vs. 1.5 ms⁻¹), these catch differences serve to illustrate that at least some species-specific diel effects might occur for trawls.

A second consideration is that the trawl lengthener was increased halfway through the work. This slight alteration was confounded with nights and so it was not possible to quantify any size- or species-selective effects. Nevertheless, any variability should be consistent between lifting bags and was captured within nights as the random blocking term. Last, owing to weather conditions and logistics, the vessel targeted whiting across different depths, which is typical but does introduce some variability. For this reason, depth was included as a covariate to adjust for the power of the fixed effect of interest (lifting bag).

Notwithstanding the above considerations, there were clear effects associated with increasing lifting-bag mesh size that can be explained by the size and shape of the affected species. Specifically, eastern school whiting are fusiform, and fish at the desired minimum commercial size of 17 cm TL have a maximum girth of ~95 mm and similar to the perimeter of the 46 mm mesh, which allowed at least some to push through if openings were available (29). The availability of open meshes can be approximated by considering relative inner surface twine areas as proxies for occlusion. Specifically, the 94-mm lifting bag had an inner surface area of ~1.6 m² (i.e., total surface area of 3.1 m² ÷ 2) that was ~70% of the codend inner surface area (2.2 m²), likely occluding a substantial proportion of codend meshes through direct contact and partial blocking. The 216-mm lifting bag had an inner surface area of ~0.7 m² (~32% of codend area) and would have at least doubled the unobstructed mesh area available for escape.

The considerable improvement in the escape of juvenile whiting and small fish overall (contributing to the ~50% reduction in bycatch) associated with reducing mesh occlusion aligns with the general trend observed by most previous authors (13, 14, 17). For example, off the Orkney Islands, Kynoch et al. (17) found that covering 110- and 120-mm codends with 265-mm lifting bags reduced L₅₀s for haddock, Melanogrammus aeglefinus, by ~6%. Similarly, Demirci et al. (14) observed a 10% reduction in the L₅₀ of brushtooth lizardfish, Saurida undosquamis, when a 45-mm codend was covered with a 91-mm lifting bag in the Mediterranean Sea. In contrast, Tosunoglu et al. (12) noted that an 84-mm lifting bag had minimal impact on the L₅₀s of sparids (Diplodus and Pagellus) in a 40-mm codend. The magnitudes of these differences would at least partially reflect species morphology. Whiting and gadoids are fusiform and should be more affected by occlusion than deep-bodied species such as sparids.

Beyond body shape, the size of fish is also likely important. For example, although not measured for TL, the mean weight of the ventrally compressed velvet leatherjacket was only 13.5 g, which would correspond to many individuals with bodies smaller than the 46-mm mesh. Simply increasing openings allowed more velvet leatherjackets to escape, contributing to a greater reduction of total bycatch (by ~50%). Relative body size is less likely to similarly affect the escape of invertebrates like cephalopods, with many octopus larger than the 46-mm mesh able to compress and squeeze through with less occlusion. Although not significant, similar reductions were observed for squid. One important consideration is that these species are both economically important across all sizes and likely to have very low post-escape survival (30). In addition to loss of some income, increasing lifting-bag mesh size to 216 mm could increase their unaccounted fishing mortality. This outcome represents the difficulty of optimising selectivity in a multi-species trawl fishery, and warrants consideration for not only considering optimal lifting bags but also codend mesh sizes.

Notwithstanding the escape of some cephalopods and ~6% of eastern school whiting ≥17 cm TL, the data here support using a lifting-bag mesh size up to 216 mm, albeit with some modifications that might help to control selectivity. Owing to the reduction in twine area, the 216-mm lifting bag is not as strong and might not be expected to last as long as the 94-mm mesh. This latter mesh size is often chosen simply because there is an abundance of new and old (~90 mm) fish-trawl codends in southeastern Australia that can be used. Using a larger mesh would require new material to be sourced and ideally in a thicker twine diameter, which would have some concomitant effect on occlusion.

Future work warrants assessing for the effects of increasing twine Ø in larger-mesh lifting bags because this might offset marginal losses of some larger whiting and the cephalopods, while balancing desired effects on smaller unwanted fish. Such work, along with data here, reiterates the need to refine trawl selectivity through attention to all gear components, and not solely minimum SMO (31). Under individual transferable quota management where minimising juvenile capture directly improves economic efficiency, adopting appropriately configured larger-meshed lifting bags represents a practical, low-cost modification that simultaneously addresses conservation and commercial objectives.

Data availability statement

The raw data supporting the conclusions of this article will be made available by the author, without undue reservation.

Ethics statement

The animal study was approved by NSW DPIRD Fisheries Animal Care and Ethics Committee (FISH ACEC-0803 Testing selective fishing gears in NSW commercial fisheries). The study was conducted in accordance with the local legislation and institutional requirements.

Author contributions

MB: Project administration, Visualization, Supervision, Validation, Data curation, Formal analysis, Methodology, Investigation, Funding acquisition, Conceptualization, Software, Writing – original draft, Writing – review & editing, Resources.

Funding

The author(s) declared that financial support was received for this work and/or its publication. This study was funded by the New South Wales Department of Primary Industries and Regional Development.

Acknowledgments

Thanks are extended to Shane Ferrier, Brad Mackay, and Brad Leach for technical assistance, and the owners and crew of the FV Edward James for their efforts and for kindly supporting the research.

Conflict of interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Generative AI statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

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1. Pérez Roda MA, Gilman E, Huntington T, Kennelly SJ, Suuronen P, Chaloupka M, et al. A third assessment of global marine fisheries discards. FAO Fisheries and Aquaculture Technical Paper No. 633, FAO, Rome (2019). p. 78.

Google Scholar

2. Kennelly SJ, Broadhurst MK. A review of bycatch reduction in demersal fish trawls. Rev Fish Biol Fish. (2021) 31:289–318. doi: 10.1007/s11160-021-09644-0

Crossref Full Text | Google Scholar

3. Robertson JHB, Stewart PAM. A comparison of size selection of haddock and whiting by square and diamond mesh codends. J Cons. (1988) 44:148–61. doi: 10.1093/icesjms/44.2.148

Crossref Full Text | Google Scholar

4. Eryasar AR, Özbilgin H. Implications for catch composition and revenue in changing from diamond to square mesh codends in the northeastern Mediterranean. J Appl Ichthyol. (2015) 31:282–9. doi: 10.1111/jai.12643

Crossref Full Text | Google Scholar

5. Cheng ZH, Einarsson HA, Bayse S, Herrmann B, Winger P. Comparing size selectivity of traditional and knotless diamond-mesh codends in the Iceland redfish (Sebastes spp.) fishery. Fish Res. (2019) 216:138–44. doi: 10.1016/j.fishres.2019.04.009

Crossref Full Text | Google Scholar

6. Kynoch RJ, Ferro RST, Zuur G. The effect on juvenile haddock by-catch of changing cod-end twine thickness in EU trawl fisheries. Mar Tech Soc J. (1999) 33:61–72. doi: 10.4031/MTSJ.33.2.10

Crossref Full Text | Google Scholar

7. Reeves SA, Armstrong DW, Fryer RJ, Coull KA. The effects of mesh size, cod-end extension length and cod-end diameter on the selectivity of Scottish trawls and seines. ICES J Mar Sci. (1992) 49:279–88. doi: 10.1093/icesjms/49.3.279

Crossref Full Text | Google Scholar

8. Graham KJ, Broadhurst MK, Millar RB. Effects of codend circumference and twine diameter on selection in south-eastern Australian fish trawls. Fish Res. (2009) 95:341–9. doi: 10.1016/j.fishres.2008.10.001

Crossref Full Text | Google Scholar

9. Ingólfsson ÓA, Brinkhof J. Relative size selectivity of a four-panel codend with short lastridge ropes compared to a flexigrid with a regular codend in the Barents Sea gadoid trawl fishery. Fish Res. (2020) 232:105724. doi: 10.1016/j.fishres.2020.105724

Crossref Full Text | Google Scholar

10. Broadhurst MK, Millar RB. Validating a narrow codend cover and improving selectivity in south-eastern Australian fish trawls targeting eastern school whiting, Sillago flindersi. Fish Res. (2022) 251:106302. doi: 10.1016/j.fishres.2022.106302

Crossref Full Text | Google Scholar

11. Beverton RJH, Parrish BB, Trout GC. Progress report on trials of topside chafers. Ann Proc Int Comm Northw Atlant Fish. (1959) 9:86–7.

Google Scholar

12. Tosunoglu Z, Özbilgin H, Tokaç A. Effects of the protective bags on the codend selectivity in Turkish bottom-trawl fishery. Arch Fish Mar Res. (2003) 50:239–52.

Google Scholar

13. Aydin C, Sensurat T, Özdemir Y, Tosunoglu Z. Effect of the number of meshes in the protective bag circumference on size selectivity of demersal trawl codends. J App Ichthy. (2014) 30:454–62. doi: 10.1111/jai.12413

Crossref Full Text | Google Scholar

14. Demirci S, Demirci A, Simsek E. Negative effect of protective bag on trawl codend selectivity. Ind J Geo-Mar Sci. (2019) 48:499–503.

Google Scholar

15. Broadhurst MK, Millar RB. Improved size selection and estimated at-vessel mortalities for an Australian whiting (Sillago spp.) boat seine. Fish Res. (2023) 266:106778. doi: 10.1016/j.fishres.2023.106778

Crossref Full Text | Google Scholar

16. Sala A, Lucchetti A, Piccinetti C, Ferretti M. Size selection by diamond- and square-mesh codends in multi-species Mediterranean demersal trawl fisheries. Fish Res. (2008) 93:8–21. doi: 10.1016/j.fishres.2008.02.003

Crossref Full Text | Google Scholar

17. Kynoch RJ, O‘Dea MC, O'Neill E. The effect of strengthening bags on cod-end selectivity of a Scottish demersal trawl. Fish Res. (2004) 68:249–57. doi: 10.1016/j.fishres.2003.12.003

Crossref Full Text | Google Scholar

18. Broadhurst MK, Millar RB. (2025). Refining size selection in an Australian whiting (Sillago spp.) boat seine. Fish Res. 281:107251. doi: 10.1016/j.fishres.2024.107251

Crossref Full Text | Google Scholar

19. Broadhurst MK, Millar RB. Reducing codend mesh size and changing configurations to improve selectivity in Australian whiting (Sillago spp.) trawls. Fish Res. (2025). 282:107273. doi: 10.1016/j.fishres.2025.107273

Crossref Full Text | Google Scholar

20. Broadhurst MK. Cumulative selectivity benefits of increasing codend and lifting-bag mesh sizes in an Australian boat seine. Fish Res. (2025) 290:107517. doi: 10.1016/j.fishres.2025.107517

Crossref Full Text | Google Scholar

21. Butler DG, Cullis BR, Gilmour AR, Gogel BJ, Thompson R. ASReml-R Reference Manual Version 4.1.0.130. VSN International Ltd (2020). Available online at: https://asreml.kb.vsni.co.uk/wp-content/uploads/sites/3/2018/02/ASReml-4.1-Functional-Specification.pdf (Access April 2, 2025).

Google Scholar

22. R Core Team. R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing (2023).

Google Scholar

23. Millar RB. Estimating the size-selectivity of fishing gear by conditioning on the total catch. J Amer Stat Assoc. (1992) 87:962–8. doi: 10.1080/01621459.1992.10476250

Crossref Full Text | Google Scholar

24. Millar RB. R package SELECT for estimating size selectivity of fishing gears. (2021). Available online at: https://github.com/rbmillar/SELECT (Access April 2, 2025).

Google Scholar

25. Broadhurst MK, Millar RB. Square-mesh codend circumference and selectivity. ICES J Mar Sci. (2009) 66:566–72. doi: 10.1093/icesjms/fsp001

Crossref Full Text | Google Scholar

26. Millar RB, Broadhurst MK, Macbeth WG. Modelling between-haul variability in the size selectivity of trawls. Fish Res. (2004) 67:171–81. doi: 10.1016/j.fishres.2003.09.040

Crossref Full Text | Google Scholar

27. Millar RB, Broadhurst MK. Incorrect inference from size-selectivity studies due to widespread misuse of bootstrap intervals. Fish Res. (2025) 281:107225. doi: 10.1016/j.fishres.2024.107225

Crossref Full Text | Google Scholar

28. Wardle CS. Understanding fish behaviour can lead to more selective fishing gears. In:Campbell CM, , editor. Proceedings of the World Symposium on Fishing Gear and Fishing Vessels Marine Institute, St Johns, Canada. Marine Institute, St. John's, NL, CA (1989). p. 12–8.

Google Scholar

29. Broadhurst MK, Dijkstra KKP, Reid DD, Gray CA. Utility of morphological data for key fish species in southeastern Australian beach-seine and otter-trawl fisheries: predicting mesh size and configuration. NZ J Mar Freshw Res. (2006) 40:259–72. doi: 10.1080/00288330.2006.9517419

Crossref Full Text | Google Scholar

30. Broadhurst MK, Suuronen P, Hulme A. Estimating collateral mortality from towed fishing gear. Fish Fish. (2006) 7:180–218. doi: 10.1111/j.1467-2979.2006.00213.x

Crossref Full Text | Google Scholar

31. McHugh MJ, Broadhurst MK, Sterling DJ. Choosing anterior-gear modifications to reduce the global environmental impacts of penaeid trawls. Rev Fish Biol Fish. (2017) 27:111–34. doi: 10.1007/s11160-016-9459-5

Crossref Full Text | Google Scholar