(a) River Frome 1SW, (b) River Frome MSW, (c) North East Coast 1SW, (d) North East Coast ΜSW. Temporal scale represents the last year of marine feeding. Solid (red) line is a first-order LOESS fit with a span width of 0.5; dashed (blue) lines show +/− standard error of the residuals of the smoothed fit.