Application of bomb radiocarbon chronologies to shortfin mako (Isurus oxyrinchus) age validation

Abstract

Age estimation is an issue for the shortfin mako, Isurus oxyrinchus, because of disagreement on vertebral band-pair deposition periodicity. In the 1950s-1960s, thermonuclear testing released large amounts of radiocarbon into the atmosphere, which diffused into the ocean through gas exchange. This influx created a time-specific marker that can be used in age validation. Annual band-pair deposition in the porbeagle, Lamna nasus, was validated in a previous study and indicated preliminary annual deposition in the shortfin mako, using four samples from one vertebra. In the present study, age estimates from 54 shortfin mako vertebrae collected in 1950-1984 ranged 1-31 years. Ageing error between readers was consistent, with 76% of the estimates ranging within 2 years. Twenty-one D 14 C values from eight shortfin mako vertebrae (collected in the western North Atlantic in 1963-1984) ranged -154.8& to 86.8&. The resulting conformity with the D 14 C timeline for the porbeagle supported annual band-pair deposition in vertebrae of the shortfin mako.

Age and growth analysis of the shortfin mako, Isurus oxyrinchus, in the western and central North Pacific Ocean

“…For Atlantic shortfin mako, the annual formation of one growth band pair was validated by bomb radiocarbon experiment (Campana et al 2002;Ardizzone et al 2006) and by OTC-injection experiment , therefore, we revised the growth curves reported by Pratt and Casey (1983) to reflect annual, instead of biannual, band pair deposition. The revised curves yielded a faster growth rate for both sexes than are suggested by our data.…”

“…However, this conflict has been settled by recent studies using bomb radiocarbon and tetracycline injection in individuals from the Atlantic Ocean (Campana et al 2002;Natanson et al 2006;Ardizzone et al 2006). These results confirmed that one growth band pair is formed annually in individuals from both the Pacific and the Atlantic oceans.…”

Age and growth studies of chondrichthyan fishes: the need for consistency in terminology, verification, validation, and growth function fitting

“…While this exciting new validation approach is quite promising, it is also highly technical and expensive, thus no new papers have been published to date. However, three papers were presented at this symposium, which appear in these proceedings (see Ardizzone et al 2006;Campana et al 2006;Kerr et al 2006) In our review of the recent literature (Cailliet and Goldman 2004), including the more recent 28 studies, validation studies have not been very common for chondrichthyan fishes. This is mainly because of their limited accessibility, large size and mobility, and the difficulty of obtaining monthly, or even seasonal, samples.…”

Investigations of Δ 14C, δ 13C, and δ 15N in vertebrae of white shark (Carcharodon carcharias) from the eastern North Pacific Ocean

“…A qualitative comparison of the white shark D 14 C record was made with existing marine records including two otolith-based records, the yelloweye rockfish, Sebastes ruberrimus, (Kerr et al 2004) and Pacific halibut, Hypoglossus stenolepis, (Piner and Wischniowski 2004), and three vertebra-based shark records, the western North Atlantic porbeagle (Campana et al 2002), western North Atlantic shortfin mako (Campana et al 2002;Ardizzone et al 2006), and the western South Pacific school shark (Kalish and Johnston 2001).…”