bait size and angling technique on the hooking location and the catch of recreationally caught black bream Acanthopagrus butcheri

Fisheries Research 84 (2007) 338–344

The effect of hook/bait size and angling technique on the hooking location and the catch of recreationally caught black bream Acanthopagrus butcheri Daniel Grixti a,∗ , Simon D. Conron a , Paul L. Jones b a

Marine and Freshwater Systems PIRVic., P.O. Box 114 Queenscliff, Vic. 3225, Australia b Deakin University, P.O. Box 423, Warrnambool, Vic. 3280, Australia

Received 20 September 2005; received in revised form 6 November 2006; accepted 10 November 2006

Abstract The black bream Acanthopagrus butcheri recreational fishery is the largest estuarine fishery in Victoria. This fishery is managed through legalminimum length and daily bag limits. The success of this management strategy requires a high survival rate for released fish. Deep-hooking is known to reduce the chance of fish survival after recreational capture and release. This study investigated the potential to reduce deep-hooking and the number of under-size A. butcheri caught by varying angling gear and techniques. Three sizes of long shank hook (small [size 8], medium [size 4] and large [size 1/0]) and two angling techniques (slack line and tight line) were tested for their deep-hooking rates and selectivity characteristics. Increasing the hook size from small to large decreased the likelihood of deep-hooking by 6.6 times (95% CI 2.3–16.3 times). Fishing with a tight line instead of a slack line decreased the chance of deep-hooking by almost 100% (95% CI 0.8–3.6). Fishing with a large hook instead of a small hook significantly (F = 6.71, df = 2, P = <0.001) increased the mean A. butcheri length, although this mean size increase was less than 1 cm. This study was able to identify angling gear and angling technique manipulations that reduced the rate of deep-hooking when targeting A. butcheri in Victorian estuaries. © 2006 Elsevier B.V. All rights reserved. Keywords: Hooking location; Selectivity; Acanthopagrus butcheri; Post-release survival; Angling; Hook

1. Introduction Size- and bag-limit regulations are common management strategies in recreational fisheries (King, 1995). Their aim is to decrease mortality for a proportion of a fish stock without directly reducing fishing effort. However, post-release survival (PRS) of fish under the size limit or over the bag limit needs to be high for this management to work effectively (Wydoski, 1977). While the large variations in estimates of survival across studies and species (Muoneke and Childress, 1994) suggest the critical assumption that the rate will be high is not always being met. To help meet this assumption, techniques and gears that increase survival rates and reduce captures of fish under the legal size are a priority for fisheries using these stratergies. Studies of PRS rates typically record the position where the hook point penetrates the tissue and refer to this point as the

∗

Corresponding author. Tel.: +61 3 5258 0111; fax: +61 3 5258 0270. E-mail address: [email protected] (D. Grixti).

0165-7836/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.fishres.2006.11.039

anatomical hooking location (Muoneke and Childress, 1994). Although there are many possible hooking locations, fish hooked in the lip and mouth are often recorded as shallow-hooked while fish hooked further down the digestive tract are recorded as deephooked fish (Muoneke and Childress, 1994). The latter usually have a much lower rate of survival (Jordan and Woodward, 1992; Nuhfer and Alexander, 1992; Cooke and Suski, 2004). By reducing the rate of deep-hooking, it may be possible to increase the overall rate of PRS. The characteristics of fishing gears and techniques affect the size range of fish taken from the population (McCracken, 1963; Otway and Craig, 1993; Ralston, 1990). If the selectivity characteristics of recreational angling gear and techniques can be identified then the catch of under-sized fish can be reduced and possibly the rate of PRS increased. Comparing the catch length and bait loss are two methods that can be used to identify selectivity. When comparing species catch lengths across gears or techniques, significant differences in fish length will indicate the selectivity of those gears and techniques. The rate fishes remove baits from hooks without themselves becoming hooked is termed

D. Grixti et al. / Fisheries Research 84 (2007) 338–344

’bait loss’ selectivity. Differences in bait loss across gears or techniques can be compared to indicate selectivity (Otway and Craig, 1993; Ralston, 1982). For example, if one size of hook loses bait more regularly than another, the two hooks may be targeting fish of different sizes in the population. This method of assessing selectivity assumes that gear or techniques do not discourage fish of any particular length from accepting the bait (Ralston, 1982). Deep-hooking rates and fish selectivities are thought to depend on differences in the size and type of hooks and baits and angling techniques. Hook type (Falterman and Graves, 2002; Prince et al., 2002; Skomal et al., 2002; Zimmerman and Bochenek, 2002; Cooke et al., 2003), bait type (Erzini et al., 1998; Huse and Soldal, 2000; Broadhurst and Hazin, 2001), bait orientation (Broadhurst and Hazin, 2001) and the addition of inedible plastic bodies to hooks with organic bait (Løkkeborg and Bjordal, 1995; Huse and Soldal, 2000) have been reported to change both deep-hooking rates and the size of fish captured. Increasing hook sizes with a standard bait size in demersal longline fisheries increased the mean size and decreased the number of under-sized snapper (Pagrus auratus) captured (Ralston, 1990; Otway and Craig, 1993). Huse and Soldal (2000) found that mackerel baits of twice their traditional size decreased the catch of under-size fish pelagic haddock (Melanogrammus aeglefinus) by 40% in longline fisheries. As Acanthopagrus butcheri (black bream) is the most commonly targeted species by recreational fishers in estuarine waters of Victoria, it was chosen as a suitable fish for the present study. This fishery is managed through legal-minimum length (26 cm total length and 28 cm in the Gippsland lakes) and daily bag limits (10 per person per day). Preliminary studies of A. butcheri found that deep-hooking was the main cause of catchand-release mortality (Conron et al., 2004). Our objective was to determine whether deep-hooking could be reduced for A. butcheri by manipulating angling gear and techniques. Three null hypotheses were tested: the incidence of deep-hooking would not be different across hook sizes, the number of undersized A. butcheri captured would not be different across hook sizes. The third was that providing a longer bait acceptance time would not increase the incidence of deep-hooking. The time available for a fish to accept the bait increases when fishing with a slack line compared to tight line. Fishing with a slack or tight line switches within and between anglers depending on angler experience, gear, fish behaviour and environmental conditions.

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2. Materials and methods 2.1. Experimental design Three fishing trips were conducted on the lower Glenelg River estuary in south-west Victoria, Australia, on the 15 May, 28 June and 15 August 2003. The study area, which is about 4 km long and 50 m wide was chosen as it is popular with recreational anglers and has easy boat access. The fishing trips began at 9:00 am on every trip. The same two experienced anglers fished all three trips, each with two rod (2–4 kg rod weight) and spinning reel arrangements. A running sinker rig (with a standardised 60 cm, 5.4 kg monofilament leader) and podworm bait (local species, Australonereis sp.) were used, as they are the most commonly used in the Victorian A. butcheri fishery (Conron, Department of Primary Industries Victoria, unpublished creel survey data). The anglers used three sizes of chemically sharpened, barbed, offset, longshank hooks (Dynatec, Red-Line): sizes 8, 4 and 1 (Fig. 1). Three randomly chosen hooks from a packet of each size were measured to the nearest 0.1 mm with vernier callipers to quantify the length, width, gape and bill of the hooks. The absolute size for each of the three hooks was also calculated (i.e. hook length × hook width). The dimensions of each hook size are shown in Fig. 1. Anglers baited hooks with podworm until the entire hook shank and barb was covered. This created a bait size that correlates to hook size. From hereon hook size will be referred to as hook/bait and hook sizes 8, 4, and 1/0 size as small, medium and large, respectively. This was intended to make clear that hook size is not differentiated from bait size, and no attempt is made to do so. One of the two rods used by each angler was fished in the rod holder with a slack line and the other was simultaneously hand-held with a tight line. With a tight line the angler sets the hook immediately after feeling a bite, while with the slack line a fish takes up the slack before the hook is set. Each of the three fishing trips was broken into six 1-h fishing sessions. They were conducted at randomly chosen sites within a defined area of the lower Glenelg estuary (sites chosen using a map matrix of study area). The anglers used each hook/bait size of two of the 1 h fishing sessions for each trip (thus 2 sessions/sites per hook/bait size per angler technique per angler per trip). Fig. 2 shows the experimental design in a schematic form.

Fig. 1. (a) The dimensions of a hook: L, length; W, width; G, gape; and B, bill. (b) The size 8, 4 and 1/0 hooks (from left to right). (c) Hook dimensions.

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D. Grixti et al. / Fisheries Research 84 (2007) 338–344

hooking location and its predictors. The mean of the binary response (0 or 1: lip/mouth or deep-hooked, respectively) is a probability, so the logistic regression model specifies that a probability is related to a regression-like function of ‘the explanatory variable(s) (Ramsey and Schafer, 1997). The logistic regression model was   μ log = β0 + β1(Xi1) + β2(Xi2)+)· · · + βi(Xi), 1−μ

Fig. 2. Schematic representation of study design.

At each fishing session, the two anglers always had different hook sizes from each other. The hook/bait size used by each angler for both tight and slack rods for each 1 h fishing session for each trip was chosen at random (random draw) for the first 3 h and then the last 3 h. This block randomisation helped ensure that time of day effects between the first and last 1 h session were similar for each hook/bait size and angling technique. Time lost moving between sites, anchoring, and preparing gear at each site was not included in the 1 h fishing sessions. Fishing session/site, hook/bait size, hook location (shallowor deep-hooked), angling technique (slack line or tight line), angler, and fish length (total length, rounded down) were recorded. For each hook/bait size, angling technique and 1 h fishing session/site, the number of baits put on each hook and the number and lost when a fish was not hooked were noted for each angler. If a species other than A. butcheri was captured neither the bait use nor loss was counted in the study. The data were recorded by an independent observer on each trip.

where log[μ/(1 − μ)] is the logit link function, which predicts the probability of deep-hooking by linking the random and systematic component of the model (Quinn and Keough, 2002), β0 is the constant and was included in all models, and βi(Xi) is the slope of the ith predictor variable. Categorical predictors were converted to dummy variables by reference cell coding. Goodness of fit tests (the χ2 statistic and the log-likelihood statistic) were used to determine the appropriateness and adequacy of the model. Model selection was achieved by using the drop-in-deviance G2 test (Ramsey and Schafer, 1997). Hierarchical removal of predictors from the full model was determined by the Wald statistic and the odds ratios 95% confidence bounds for terms in each successive model fitted. Strong co-linearity between variables was tested by contingency table Chi-square analysis of association (Quinn and Keough, 2002). 3. Results 3.1. Number of baits used A total of 1292 baits were used, averaging (mean ± 1 S.E.) 17.9 ± 0.7 baits per rod per hour. The fish generally accepted the baits for all hook/bait sizes of both angling techniques within a few minutes of them entering the water. No significant differences (P = >0.05) were found in the mean number of baits used per rod per hour for trip, angler, hook/bait size or angler technique (Table 1).

2.2. Statistical procedures

3.2. Number of A. butcheri captured

All statistical analyses were performed on SPSS V11.01. An alpha of 0.05 was choosen as the critical level for rejection of the null hypotheses. The mean numbers per hour of baits used, A. butcheri caught and baits loss as well as the mean lengths of A. butcheri were compared by multi-factor ANOVA for each trip (random factor), angler, angler technique and hook/bait size (fixed factors). The Kolmogorov-Smirnov test was used to test data normality, while a Levenes test was used to test for heteroscedasticity. Inspection of box plots helped identify the cause of any violations. When the assumptions of normality and homogeneity were not met, the data were log-transformed. Type III Sum of Squares based on unweighted marginal means was used during ANOVA to deal with the unbalanced fish numbers as a result of catch-rate variability. Post-hoc comparison of means was performed with Scheffe’s tests. A logistic regression model was fit to the data with maximumlikelihood estimation to best describe the relationship between

A total of 589 A. butcheri were caught over the three fishing trips; only 14 (2%) were of legal harvest size (>26 cm). The number of legal-sized fish captured was too low to make separate valid statistical comparisons for these fish. The catch rate per hour averaged (mean ± 1 S.E.) 16.4 ± 1.0 fish (Table 1). Significantly, more A. butcheri were caught per hour fishing with a tight line than a slack line (F = 34.03, df = 1, P = <0.028), while no other variables affected catch rates. Although there was not an interaction between hook/bait size and angler technique, total catches on slack lines tended to reduce as hook/bait size increased (Fig. 3). 3.3. Bait loss A significantly greater number of baits were lost when fishing with a slack line than with a tight line (F = 64.53, df = 1, P = 0.015) (Table 1). Bait loss was not significantly affected by

D. Grixti et al. / Fisheries Research 84 (2007) 338–344

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Table 1 Summary table of the mean number of baits used, the mean number of baits lost and the mean length of fish caught per hour for each variable Mean of baits used

S.E.

Mean of baits lost

S.E.

Mean of fish caught

S.E.

Deep-hooking probability

S.E.

Hook/bait small Small Medium Large

18.04 17.75 18.04

0.66 0.88 0.86

9.21 8.38 10.96

0.94 0.7 0.76

17.61 17.94 18.52

0.19 0.18 0.22

0.25 0.14 0.04

0.03 0.02 0.02

Angling technique Slack line Tight line

17.36 18.52

0.63 0.66

10.69 8.33

0.55 0.73

18.28 17.80

0.18 0.15

0.24 0.10

0.03 0.02

Angler Angler 1 Angler 2

17.86 18.02

0.68 0.62

10.06 8.97

0.63 0.71

17.83 18.12

0.15 0.14

0.10 0.20

0.02 0.02

Trip Tripl Trip 2 Trip 3

16.79 17.95 19.08

0.88 0.64 0.8

9.72 9.46 9.29

0.85 0.83 0.82

18.21 17.97 17.84

0.22 0.2 0.15

0.15 0.17 0.14

0.03 0.03 0.02

The probability of deep-hooking according to predictor variables is also shown. S.E.: represents ±1 standard error.

hook/bait size, although the test result was close to significant (F = 5.74, df = 2, P = 0.067). No differences in mean bait loss were recorded for angler, trip or their interactions (Table 1).

(Table 1.). Trip, angler and all interactions did not affect the size of fish. 3.5. Hooking location

3.4. Size of fish caught The length-frequency distributions were dominated by fish between 15 cm and 22 cm for all hook/bait sizes (Fig. 4), with the mode more prominent for the smaller hooks. Larger fish were not common, which meant data (fish lengths) was skewed to the right and the assumption of normality by the ANOVA test was not met. After natural log-transformation, the data fitted a normal distribution. The mean lengths (±1 S.E.) of fish caught on hook/bait sizes small, medium and large were 17.6 ± 0.2 cm, 17.9 ± 0.2 cm and 18.5 ± 0.2 cm, respectively and were significantly different (F = 6.71, df = 2, P = <0.001) (Table 1). Post-hoc analysis revealed that the difference was between hook/bait size small and large, but the difference was less than 1 cm. Fishing with slack line (mean ± 1 S.E., 18.3 ± 0.2 cm) caught significantly larger fish than tight line (17.7 ± 0.2 ± cm), although the absolute difference was again small (F = 4.53, df = 1, P = 0.034)

A. butcheri shallow-hooked in the lip/mouth area totaled 499 (85%), while 90 (15%) were deeply hooked. The probability of deep-hooking increased with fish length (Fig. 5). The mean length (±1 S.E.) was 18 ± 0.12 cm for lip/mouthhooked A. butcheri and 20 ± 0.41 cm for deep-hooked fish. Hook/bait size, fish length and angling technique were significant predictors for deep-hooking in the logistic regression model (Table 2). The variables of angler, trip and all interactions were not included in the final model because they did not explain a significant amount of the variation in the data (Table 2). The large effect of hook/bait size on the probability of deep-hooking, in particular the difference between hook/bait sizes small and large (Table 1), was highlighted by the odds ratio. This ratio (odds ratio point estimate 7.62: 95% CI 3.36–17.28) implies that deep-hooking is 6.6 times more likely for the small hook/bait than the large hook/bait. Slack-line fishing was almost twice (odds ratio 2.91: 95% CI 1.83–4.62) more likely to deep-hook fish than was tight-line fishing. With every 1 cm increase in A. butcheri total length, a fish had 0.25 (odds ratio = 1.24: 95% CI 1.17–1.34) more chance of deep-hooking than not. 4. Discussion

Fig. 3. Mean (±1 S.E.) number of bream caught per angler hour using slack line and tight line for each hook/bait size.

The present study has shown that the incidence of deephooking of A. butcheri may be greatly reduced by increasing the hook/bait size used. Restricting the time available for fish to ingest the bait by fishing with a tight line also reduces the incidence of deep-hooking. Fish length was an important factor in the probability of deep-hooking (positive correlation). Increasing the hook/bait size did not appear to affect the likelihood of a bait being accepted. Fish-size selectivity was demonstrated by

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Table 2 Summary of significant contributors to the logistic regression model Model B0 + B1(fish length) + B2(hook/bait size)

Ho

Goodness of fit test

B4 (angler technique) = 0

χ2

B0 + B1 (fish length) + B4 (angler technique)

B2 (hook/bait size) = 0

B0 + B2(hook/bait size) B4 (angler technique)

B1(fish length) = 0

−2(loglikelihood) χ2 −2(loglikelihood) χ2 −2(loglikelihood)

83.055 420.584 54.184 449.455 53.209 450.431

df

Drop in deviance test

df

3

G2

** 29.225

10

2

G2

*** 58.097

11

3

G2

*** 59.072

10

The full logistic regression model included fish length, hook/bait size, angling technique, trip, angler and all possible interactions. Predictor’s contribution to the model assessed in sequence using the drop-in-deviance test until only predictors that contribute significantly to the model remain. * Significant: p < 0.05. ** highly significant: p < 0.01. *** very highly significant: p < 0.001.

changing the hook/bait size and angling technique, although the difference in mean fish length among treatments was <1 cm in both cases. Catch rates of legal-sized A. butcheri did not appear to increase for any of the hook/bait sizes or angler techniques; however, slack-line fishing did result in reduced catch rates for under-size fish. Anglers in recreational fisheries generally apply larger or greater amounts of bait as the hook size they are using increases. To best mimic real angling practices, this study used a bait size proportional to hook size. Ralston (1982, 1990) and Otway and Craig (1993) noted (for commercial longlining) that this confounds the effect of hook size. In the present study it was not possible to have the same bait size across hook sizes due to the physical characteristics of podworm (a very soft bodied worm that commonly ranges from 5 to 15 cm in length). Furthermore, standardising bait size would not have mimicked the techniques used by anglers in the fishery. Studies similar to the present one should ensure that bait size is the same within each hook size. By using such an experimental design, hook size comparisons are confounded by a different bait size and the individual effect of hooks cannot be delineated. Therefore, discussion of the size selectivity, catch rates or deep-hooking results must be attributed to hook and bait size simultaneously. The mean length of A. butcheri caught in the present study was significantly different for hook/bait sizes and angling techniques but this difference was less than 1 cm. As most of the

Fig. 4. Length-frequency distribution of A. butcheri for each hook/bait size and hook/bait sizes combined.

Fig. 5. Probability of deep-hooking at each fish length. (Note: This trend requires careful interpretation, as deep-hooking probabilities for fish lengths 11, 12 and 25–35 are derived from 5 or fewer fish (see Fig. 4. for number of fish per length). Error bars represent ±1 S.E.

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A. butcheri caught were under-sized, selectivity for fish length could not be demonstrated over the range of sizes in a population. The large numbers of small A. butcheri in the study area, combined with their ability to find the bait quickly, may explain why legal-sized A. butcheri made up only a small percent of the catch. According to a local Glenelg Estuary angler with 30 years experience (Fred Wilson pers. comm.), A. butcheri anglers using podworm and other  soft baits often switch to  hard baits such as crab when they are catching a lot of small fish in an attempt to prevent small fish from removing the bait before larger fish can take it. When comparing selectivity based on bait loss, it is assumed that acceptance of bait by fish is not affected by the variable of interest (hook/bait size and angling technique). This assumption was probably meet because there was no difference in the number of baits used per hour for any variables. The number of baits used and baits lost were not recorded for captured species other than A. butcheri. Possibly other species affect catch rates and bait loss. There were no differences in the number of baits used, all variables were used randomly and variables were tested within a close timeframe to each other, so bait loss analysis would still be representative of A. butcheri selectivity despite the presence of other species. Significantly more baits were lost when fishing with slack line than when fishing with tight line and as most fish obtained in this study were under-sized, it follows that fishing with tight line is more effective than slack line at catching under-sized A. butcheri. The probability of deep-hooking decreased significantly as hook/bait size increased. The magnitude of this effect was substantial and may be of importance if deep-hooking is found to decrease PRS in A. butcheri. Jordan and Woodward (1992) suggested that red drum (Sciaenops ocellatus) anglers should not use small hooks to reduce the incidence of fish hooked in the gills or oesophagus. Cooke et al. (2005), who compared five circle-hook sizes for hook location rates of bluegill (Lepomis macrochirus), found that deep-hooking only occurred with the three smallest hook sizes. Nuhfer and Alexander (1992) observed that larger brook trout (Salvelinus fontinalis) were more likely to swallow lures deeply, as their wide gape did not prevent them from doing so. Increasing hook size has previously been linked to increased PRS in blue cod (Parapercis colias) (Carbines, 1999), smallmouth bass (Micropterus dolomieu) (Weidlein, 1989) and striped bass (Morone saxatilis) (Diodata, 1991). In contrast, as hook size increases the injury to deeply hooked fish may be more severe and could potentially decrease PRS of deep-hooked fish. Hulbert and Engstrom-Heg (1980) reported decreased PRS in rainbow trout (Oncorhynchus mykiss) with the use of larger hooks. Ultimately, the effect of increasing hook size on PRS will depend on the combination of deephooking rates, catch of under-sized fish and survival rates when fish are deep-hooked. Setting the hook immediately when a fish accepts the bait by fishing a tight line probably restricts the time available to chew and swallow the bait, decreasing the chance of deephooking. Schill (1996) reported that deep-hooking of rainbow trout (Onchorhyncus mykiss) was higher when fishing with slack line than when fishing with a tight line. Warner and Johnson

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(1978) found vastly different survival rates (0–100%) from different anglers, as a result of different deep-hooking rates. In that study the time allowed for a fish to swallow the bait varied across anglers, which probably affected the incidence of deep-hooking. Schisler and Bergersen (1996) suggested that differences in deep-hooking rates observed between natural and artificial baits may have been a result of the natural baits being fished passively, while the artificial baits were fished actively. Dunmall et al. (2001) found no difference in deep-hooking for natural and artificial baits when both were fished actively. In the present study, the benefit of deep-hooking fewer fish when using a tight line instead of a slack line was somewhat offset by the increased catch rates of the tight line. However, given that lip/mouth-hooked fish are generally more likely to survive than deep-hooked fish (Jordan and Woodward, 1992; Muoneke and Childress, 1994; Carbines, 1999; Dunmall et al., 2001) and the fact that some anglers enjoy catching any fish, irrespective of size, the PRS benefit of tight line angling is still likely to be considerable. Two possible measures to improve PRS were identified in the present study: increasing hook/bait size and fishing with tight line. The management utility of such measures to protect A. butcheri stocks may only be from voluntary angler adoption, given that the fisheries are mixed species (many gears and angling techniques) and most of the anglers are inexperienced (unlikely to fish effectively with a tight line, as this requires constant attention to the cast rod). Further studies could consider a greater size range of hooks, different baits (e.g. crabs, bivalves) and the effect of hook type. As a result of increased injury or stress, PRS rates may vary at each hooking location depending on the variable (i.e. hook size). Therefore, the survival of released fish should be monitored to validate the apparent benefit of variables that reduce deep-hooking. Acknowledgements Many thanks to Jason Kelly for the hours of volunteer angling and his advice on fishing gear and techniques. We thank the technical support of David McKeown and Ian Duckworth from the Marine and Freshwater Systems, PIRVic. Also thanks to Ed Chester of Deakin University and Adrian Thomson of Western Australia Marine Research Laboratories for providing valuable data analysis support. Dr V. Mawson, reviewers and the editor’s comments on the manuscript were appreciated. This work was funded by Deakin University and by the RFL Fisheries Revenue Allocation Committee (Project No. 12/01/02R). References Broadhurst, M.K., Hazin, F.H.V., 2001. Influences of type and orientation of bait on catch of swordfish (Xiphias gladius) and other species in an artisanal subsurface longline fishery off northeastern Brazil. Fish. Res. 53 (2), 169–179. Carbines, G.D., 1999. Large hooks reduce catch-and-release mortality of blue cod Parapercis colias in the Marlborough Sounds of New Zealand. N. Am. J. Fish. Manage. 19 (4), 992–998. Conron, D.S., Grixti, D., Morison, A., 2004. Assessment of mortality of undersize snapper and black bream caught and released by recreational anglers. Report No.2. Primary Industries Research Victoria, Queenscliff.

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D. Grixti et al. / Fisheries Research 84 (2007) 338–344

Cooke, S.J., Barthell, B.L., Suski, C.D., 2003. Effects of hook type on injury and capture efficiency of rock bass, Amloplites rupestris, angled in south-eastern Ontario. Fish. Manage. Ecol. 10, 269–271. Cooke, S.J., Barthell, B.L., Suski, C.D., Siepker, M.J., Phillip, D.P., 2005. Influence of circle hook size on hooking efficiency, injury, and size selectivity of bluegill with comments on circle hook conservation benefits in recreational fisheries. N. Am. J. Fish. Manage. 25 (1), 211–219. Diodata, P.J., 1991. Estimating mortality of hooked and released striped bass. AFC-22. National Marine Fisheries Service. Dunmall, K.M., Cooke, S.J., Schreer, J.F., McKinley, R.S., Cooke, S.J., 2001. The effect of scented lures on the hooking injury and mortality of smallmouth bass caught by novice and experienced anglers. N. Am. J. Fish. Manage. 21, 242–248. Erzini, K., Goncalves, J.M.S., Bentes, L., Lino, P.G., Ribeiro, J., 1998. Species and size selectivity in a “red” sea bream longline ’m´etier’ in the Algrave (southern Portugal). Aquat. Living Resour. 11, 1–11. Falterman, B., Graves, J.E., 2002. A preliminary comparison of the relative mortality and hooking efficiency of circle and straight shank (“J”) hooks used in the pelagic long line industry. Am. Fish. Soc. Symp. 30, 80–87. Hulbert, P.J., Engstrom-Heg, R., 1980. Hooking mortality of worm-caught hatchery brown trout. NY Fish. Game J. 27, 1–10. Huse, I., Soldal, A.V., 2000. An attempt to improve size selection in pelagic longline fisheries for haddock. Fish Res. 48, 43–54. Jordan, S.R., Woodward, A.G., 1992. Survival of hook-caught red drum. In. Proc. 46’ Annu. Conf. Southeast. Assoc. Fish Wildl. Agencies. 46, 337–344. King, M., 1995. Fisheries Biology, Assessment and Management. Blackwell Science Ltd. Løkkeborg, S., Bjordal, A., 1995. Size-selective effects of increasing bait size by using an inedible body on longline hooks. Fish Res. 24, 273–279. McCracken, F.D., 1963. Selection by codend meshes and hooks on cod, haddock, flatfish and redfish. In: The Selectivity of Fishing Gear. Spec. Publ. No. 5. Int. Comm. Northwest Alt. Fish., Dartmouth, N.S. Canada, pp. 131–155. Muoneke, M.I., Childress, W.M., 1994. Hooking mortality: A review for recreational fisheries. Rev. Fish. Sci. 2, 123–156. Nuhfer, A.J., Alexander, G.R., 1992. Hooking mortality of trophy-sized wild brook trout caught on artificial lures. N. Am. J. Fish. Manage. 12, 634–644.

Otway, N.M., Craig, J.R., 1993. Effects of hook size on the catches of undersized snapper Pagrus auratus. Mar. Ecol. Prog. Ser. 93, 9–15. Prince, E.D., Ortiz, M., Venizelos, A., 2002. A comparison of circle hook and “J” hook performance in recreational catch-and-release fisheries for Billfish. Am. Fish. Soc. Symp. 30, 66–79. Quinn, G.P., Keough, M.J., 2002. Experimental design and data analysis for biologists. Cambridge University Press. Ralston, S., 1982. Influence of hook size in the Hawaiian deep-sea handline fishery. Can. J. Fish. Aquat. Sci. 39, 1297–1302. Ralston, S., 1990. Size-selection of snappers (Lutjanidae) by hook and line gear. Can. J. Fish. Aquat. Sci. 47, 696–700. Ramsey, A., Schafer, G., 1997. The statistical sleuth: a course in the methods of data analysis. Duxbury Press, Oregon. Schill, D.J., 1996. Hooking mortality of bait-caught rainbow trout in an Idaho stream and a hatchery: Implications for special-regulation management. N. Am. J. Fish. Manage. 16, 348–356. Schisler, G.J., Bergersen, E.P., 1996. Post-release hooking mortality of rainbow trout caught on scented artificial baits. N. Am. J. Fish. Manage. 16, 570–578. Skomal, G.B., Chase, B.C., Prince, E.D., 2002. A comparison of circle hook and straight hook performance in recreational fisheries for juvenile Atlantic bluefin tuna. Am. Fish. Soc. Symp. 30, 57–65. Warner, K., Johnson, P.R., 1978. Mortality of landlocked Atlantic salmon (Salmo salar) hooked on flies and worms in a river nursery area. Trans. Am. Fish. Soc. 107, 772–775. Weidlein, W.D., 1989. Mortality of released sublegal-sized smallmouth bass, catch-and-release implications. In: Barnhart, R.A., Roelofs, T.D. (Eds.), Catch-and-Release Fishing—A Decade of Experience. Humboldt State University, California Cooperative Fisheries Research Unit, Arcata, CA, pp. 217–228. Wydoski, R.S., 1977. Relation of hooking mortality and sublethal hooking stress to qualify fishery management. In: Barnhart, R.A., Roelofs, T.D. (Eds.), Catch-and-Release Fishing As A Management Tool. Humboldt State University, Arcata, California, pp. 43–87. Zimmerman, S.R., Bochenek, E.A., 2002. Evaluation of the effectiveness of circle hooks in New Jersey’s recreational Summer Flounder Fishery. Am. Fish. Soc. Symp. 30, 106–109.