Long-awaited oys­ter man­age­ment study re­leased

Dorchester Star - - Regional - By JOSH BOLLINGER jbollinger@star­dem.com Fol­low me on Twit­ter @jbol­l_s­tar­dem.

EAS­TON — It may be too early to tell whether Mary­land’s oys­ter sanc­tu­ar­ies are work­ing as hoped, ac­cord­ing to a study re­leased by the state Depart­ment of Nat­u­ral Re­sources on Sun­day, July 31.

How­ever, indi­ca­tors like abun­dance, sur­vival, biomass and size struc­ture have shown stable or in­creas­ing trends in sanc­tu­ar­ies, ac­cord­ing to the study. But, the study also in­di­cates that biomass, or the to­tal mass of oys­ters in a given area, in pub­lic fish­ery ar­eas be­gan to de­cline in 2014 and 2015.

The long-awaited study is a com­pre­hen­sive five-year look at the state’s oys­ter pop­u­la­tion man­age­ment, in­clud­ing how the sanc­tu­ar­ies are do­ing since the state over­hauled ef­forts in 2010 to in­crease the Ch­e­sa­peake Bay’s oys­ter pop­u­la­tion. It also looks at pub­lic fish­ery grounds and the state’s aqua­cul­ture move­ment. DNR plans to re­lease a new study on the state’s oys­ter pop­u­la­tion man­age­ment ev­ery five years.

It is a widely ac­cepted be­lief that the Bay’s oys­ters have de­clined to 1 per­cent of their his­toric lev­els due to var­i­ous fac­tors, in­clud­ing dis­ease and over­fish­ing. Oys­ters are im­por­tant to the Bay’s ecosys­tem and pro­vide water fil­tra­tion and habi­tat and are valu­able to Mary­land’s econ­omy and cul­ture.

The state’s sanc­tu­ary pro­gram’s scale was ex­panded in 2010. It sought to fa­cil­i­tate de­vel­op­ment of nat­u­ral dis­ease re­sis­tance in oys­ters, pro­vide eco­log­i­cal ben­e­fits that can’t be ob­tained on a har­vest oys­ter bar and serve as a reser voir for re­pro­duc­tion.

The study states that oys­ter pop­u­la­tions in Mary­land, both sanc­tu­ar­ies and pub­lic fish­ery grounds, have ben­e­fit­ted from low dis­ease mor­tal­ity and from two good years of re­pro­duc­tion in 2010 and 2012. While oys­ter biomass in Mary­land has gen­er­ally in­creased in the last decade, it started to de­cline in pub­lic fish­ery ar­eas in 2014 and 2015 as the oys­ters from the 2010 and 2012 year classes reached mar­ket size and were har­vested.

The study in­di­cates that older, larger oys­ters that are not har­vested in sanc­tu­ar­ies see in­creased biomass each year, and since they pro­duce the most eggs, reproductive po­ten­tial in sanc­tu­ary ar­eas also con­tin­ues to rise.

But, the study still states that it might be too early to tell how oys­ter pop­u­la­tions re­acted to be­ing in sanc­tu­ar­ies.

“Given the com­plex­ity of the Ch­e­sa­peake Bay ecosys­tem, five years has not been long enough to show how oys­ter pop­u­la­tions re­spond to the ab­sence of har­vest,” the study states. “Many sanc­tu­ar­ies show pos­i­tive signs such as in­creased biomass and reproductive ca­pac­ity, while oth­ers have not shown any changes.”

The study states that the long-term be­hav­ior of sanc­tu­ar­ies will de­pend on a va­ri­ety of fac­tors, like changes in weather, water move­ment pat­terns, dis­ease and preda­tor abun­dance.

Sanc­tu­ary oys­ters de­vel­op­ing re­sis­tance to dis­eases re­mains a con­cep­tual ex­pec­ta­tion for Mary­land’s sanc­tu­ar­ies and would re­quire long pe­ri­ods of study over a broad ge­o­graph­i­cal area, the study states. Oys­ter re­sis­tance to both MSX and dermo dis­eases are her­i­ta­ble, ge­netic char­ac­ter­is­tics that can be strength­ened by planned se­lec­tive breed­ing, ac­cord­ing to the study.

“At this time, it is im­prac­ti­cal to di­rectly and ob­jec­tively eval­u­ate whether oys­ters within sanc­tu­ar­ies de­velop re­sis­tance faster than oys­ters in har­vested pop­u­la­tions,” the study states.

The study also states that it’s too early to con­clude if sanc­tu­ary oys­ter bars are pro­vid­ing more eco­log­i­cal ser­vices than har­vest bars, and that quan­ti­fy­ing it would take decades and must ac­count for cli­mate, spat set­tle­ment, dis­ease, mor­tal­ity, salin­ity, shell accumulation and sed­i­ment.

“Oys­ter reefs present in Ch­e­sa­peake Bay grew over cen­turies so that by the late 1880s the Ch­e­sa­peake Bay was the great­est oys­ter­pro­duc­ing re­gion in the world,” the study states. “The degra­da­tion of the oys­ter re­source oc­curred over at least 150 years. Hence it is un­re­al­is­tic to ex­pect a re­ver­sal within a decade.”

The study rec­om­mends look­ing at ad­just­ing the bound­aries of some sanc­tu­ar­ies and open­ing some ar­eas to har­vest, but stressed the im­por­tance of main­tain­ing the scale of the sanc­tu­ary ef­fort within the range of 20 to 30 per­cent of the re­main­ing pro­duc­tive oys­ter bot­tom.

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