$\"The$ <\/a>

The vertebra of a porbeagle shark after it has been removed from the animal and the surrounding tissue removed. Some of the annular growth rings are visible on the face of the centrum.<\/p><\/div>\n

$\"The$ <\/a>

The vertebrae is then sectioned along a vertical plane in order to view the rings.<\/p><\/div>\n

$\"Usually,$ <\/a>

Usually, a thin section is prepared by using paired blades separated by a 0.6 mm spacer.<\/p><\/div>\n

$\"Annual$ <\/a>

Annual rings in the vertebra of a known-age porbeagle shark. The arrowhead points to the birth ring. The subsequent rings indicate that this shark was 4 years old.<\/p><\/div>\n

Below are some images of vertebrae from older porbeagle, blue, mako and white sharks. Click on the images to compare the differences between these species (Note: these are high resolution images, so the images will take somewhat longer to display).<\/p>\n

Vertebrae from older sharks<\/h4>\n
$\"Vertebra$ <\/a>
Vertebra from an older porbeagle shark<\/p><\/div>\n
<\/p>\n
$\"Mako$ <\/a>
Mako Vertebra<\/p><\/div>\n
$\"Blue$ <\/a>
Blue (Whole Centrum)<\/p><\/div>\n
$\"Blue$ <\/a>
Blue (sectioned)<\/p><\/div>\n
$\"Great$ <\/a>
Great White Vertebra<\/p><\/div>\n
\n
Growth curves show the average size of a shark at each age, as determined from vertebral ring counts. Preliminary growth curves for the blue shark, the shortfin mako and the porbeagle shark are shown below. Although growth curves provide a good overall indicator of size at age, factors such as the state of health, reproductive state and local conditions can all modify the growth rate of individuals. Examples of growth curves and shark age determination are shown in Natanson et al. (2002)<\/a> and MacNeil and Campana (2003)<\/a>.<\/p>\n
<\/div>\n
<\/div>\n
\n
<\/a><\/p>\n
$\"Graph$ <\/a>
Graph of shark species age estimates based on fork length<\/p><\/div>\n<\/figure>\n<\/div>\n
Estimates of age, growth rate and longevity in sharks all assume that the vertebral rings are an accurate indicator of age. While this is probably true in most cases, confirmation of their accuracy (known as age validation) is lacking for most shark species. We now have age validation based on bomb radiocarbon for several shark species: porbeagle<\/a> (in both the NW Atlantic and the South Pacific), mako<\/a> and spiny dogfish<\/a>.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
The age of a shark is determined by counting the growth rings formed on the vertebra. The vertebral rings are laid down on a yearly basis not unlike those of trees. This method is analogous to the method used in ageing bony fish using the otolith (earstone), although not as well refined. However, sharks do […]<\/p>\n","protected":false},"author":1404,"featured_media":0,"parent":4,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-622","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/pages\/622","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/users\/1404"}],"replies":[{"embeddable":true,"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/comments?post=622"}],"version-history":[{"count":7,"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/pages\/622\/revisions"}],"predecessor-version":[{"id":1274,"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/pages\/622\/revisions\/1274"}],"up":[{"embeddable":true,"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/pages\/4"}],"wp:attachment":[{"href":"https:\/\/uni.hi.is\/scampana\/wp-json\/wp\/v2\/media?parent=622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}