Variance component analysis from linear mixed-model analysis for <i>G</i>. <i>cuvier</i> δ¹³C and δ¹⁵N for two tissue (muscle and liver) and three tissue (muscle, liver and skin) models.

<p>The between-individual component (BIC) represents the total intercept variance and the within-individual component (WIC) represents the residual variance. Total niche width (TNW) is the sum of the intercept and residual variances for δ¹³C and δ¹⁵N. Total BIC and total WIC are calculated by combining the intercept variances for δ¹³C and δ¹⁵N and then dividing by TNW. Proportion of WIC and BIC that explained TNW is in parentheses.</p

Metric multidimensional scaling (<i>m</i>MDS) ordinations of size class 2 (medium) <i>G</i>. <i>cuvier</i> dietary samples with approximate 95% region estimates fitted to bootstrap averages for decades 1 (1983–1992), 2 (1993–2003) and 3 (2004–2014).

<p>(a) Percentage frequency of occurrence (%F), (b) Percentage mass (%M), (c) Percentage number (%N) and d) Percentage index of relative importance (%IRI). <i>R</i>, ANOSIM global <i>R</i> statistic and associated <i>p</i> value. Significant pairwise tests (with <i>p</i> value in brackets) are detailed in each figure.</p

The relationship between TP and increasing body size of <i>G</i>. <i>cuvier</i>.

<p>Stomach content calculated trophic position (TP_SCA) for each size class is indicated by the white box. The solid black line in each box represents the median, outliers are indicated by open circles. TP estimated using a scaled δ¹⁵N framework (TP_scaled) is indicated by blue circles and TP estimated using a standard additive trophic framework (TP_additive) is indicated by black circles. Vertical dashed black lines indicate the predetermined size classes of <i>G</i>. <i>cuvier</i> used in the stomach content analysis (<150 cm), medium (150–220 cm) and large (>220 cm).</p

Metric multidimensional scaling (<i>m</i>MDS) ordinations of dietary samples with approximate 95% region estimates fitted to bootstrap averages for small (< 150 cm), medium (150–220 cm) and large (> 220 cm) <i>G</i>. <i>cuvier</i>.

<p>(a) Percentage frequency of occurrence (%F), (b) Percentage mass (%M), (c) Percentage number (%N) and (d) Percentage index of relative importance (%IRI). <i>R</i>, ANOSIM global <i>R</i> statistic and associated <i>p</i> value. Significant pairwise tests (with <i>p</i> value in brackets) are detailed in each figure.</p

Stomach content composition of <i>G</i>. <i>cuvier</i> caught in the KwaZulu-Natal shark nets and drumlines, 1983–2014.

<p>Results are summarized for eight functional prey groups and presented by frequency of occurrence (%F), by mass (%M), by number (N%) and index of relative importance (%IRI). Totals represent number of non-empty stomachs (F), mass prey items (M, kg) and number of unique prey items recorded (N).</p

Diet and trophic ecology of the tiger shark (<i>Galeocerdo cuvier</i>) from South African waters - Fig 7

<p>δ^<b>15</b><b>N (a and b) and</b> δ^<b>13</b><b>C (c and d) ontogenetic profiles for <i>G</i>. <i>cuvier</i> by sex (black circles represent males, grey circles represent females).</b> Linear and polynomial regression models (where appropriate) were fitted to both sexes. Grey bar depicts the predicted δ¹³C range of the KwaZulu-Natal (KZN) coastal habitat of <i>G</i>. <i>cuvier</i>.</p

Randomized cumulative prey curves derived from the stomach contents of <i>G</i>. <i>cuvier</i> caught in the KwaZulu-Natal shark nets and drumlines, 1983–2014.

<p>a) Small, b) medium, c) large size classes and d) all sharks combined. The order in which the stomachs were analysed was randomised 500 times and the means (solid lines) and 95% confidence levels (dashed lines) presented.</p

Netted beaches on the KwaZulu-Natal coast and, in parenthesis, the length of nets in kilometres and number of drumlines as of December 2014.

<p>Several net installations (*) were removed permanently during the study period 1983–2014. Insert shows the locality of the netted region in relation to the South African coast.</p

Stomach contents retrieved from <i>G</i>. <i>cuvier</i> caught in the KwaZulu-Natal shark nets and drumlines, 1983–2014.

<p>(a) <i>Philantomba monticola</i> (blue duiker) (240 cm female). (b) <i>Sousa plumbea</i> (humpback dolphin) and unidentified seabird (195 cm female). (c) <i>Spheniscus demersus</i> (African penguin), skate egg case, unidentified shark, <i>Megaptera novaeangliae</i> (humpback whale) (194 cm female). (d) <i>Morus capensis</i> (Cape gannet) and unidentified porcupine fish (232 cm male).</p

Results of linear mixed-effects models for <i>G</i>. <i>cuvier</i> δ¹³C and δ¹⁵N values for two tissue (muscle and liver) and three tissue (muscle, liver and skin) models with mass, maturity state, precaudal length, sex, tissue and capture year as the fixed effects and shark ID as a random effect.

<p>Only significant variables were retained in the optimal model. SE: Standard error.</p