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科学 · 科拉克鲤鱼清理工作

科拉克抽走 40 吨死鲤鱼,更大的问题依然存在。

一辆吸力卡车已从巴龙加鲁克溪清除了估计 40,000 公斤死鲤鱼。异味仍未消散,长期控制措施尚未决定。

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原语言视频

译自英文原文。

一辆配有吸力设备的卡车一直在从巴龙加鲁克溪抽走死鲤鱼——到目前为止约有 40,000 公斤。即使清理了这些鱼,维多利亚州西南部科拉克的居民仍生活在腐鱼的气味中。⁠1

科拉克奥特韦郡议会提供了这一估算,ABC 新闻于 11 月 6 日报道了该数据。它衡量的是清理工作的进展,而不是清理工作的完成情况。这是已收集死鱼的大致重量,并非最终死亡数量。它也没有解决更大的问题:毗邻的科拉克湖中仍存活的鲤鱼种群。有关部门称,这些鱼进入溪流产卵。⁠1

长期居住在当地的帕姆·卡斯伯森描述了鱼群挤得有多密:

成千上万条鱼全都挤在一起。连一根树枝都插不进去。

帕姆·卡斯伯森 1

她称这一景象为“环境灾难”。这是当地居民的描述,并非正式的环境分类,但它反映了当地经历的严重程度:水中有数千具鱼尸,气味蔓延至周边地区。⁠1

郡议会基础设施与环境总经理道格·麦克尼尔表示,吸力设备有效地清除了鱼类,并减轻了气味。不过,他仍提醒居民,异味还会持续一段时间,并请大家在清理工作进行期间耐心等待。目前尚未宣布清理工作的最终完成日期。⁠1

尚无结束日期的清理工作

11 月之前,这个问题就已公开。10 月 30 日,《科拉克先驱报》报道称,郡议会警告称,根据天气和水情,死鲤鱼可能还会持续出现数周。这证明当时鱼类死亡已经成为一个问题,但并不能确定第一条鱼是什么时候死亡的。⁠4

Mirage News 刊载的一份 11 月 2 日郡议会声明称,郡议会正与维多利亚州环保署、能源、环境与气候行动部以及科朗加米特流域管理局协调。承包商将在条件允许的情况下清除成片聚集的死鲤鱼。当地媒体报道称,11 月 2 日真空泵试用成功,随后开展了更多清理工作;到 11 月 4 日,清理行动开始加大力度。⁠2⁠3⁠5⁠11

ABC 于 11 月 5 日星期四下午到访时,溪中许多死鱼似乎已被清除。这一观察令人鼓舞,但既不是全面调查,也不代表工作已经完成。郡议会估算的约 40 吨死鱼量在次日早晨公布,仍只是某一阶段的进度记录。工作人员具体何时达到这一总量,目前尚不清楚。⁠1

还需要区分各机构的职责。麦克尼尔称,郡议会正与州政府及流域管理机构合作。但在 ABC 11 月 6 日的报道中,科朗加米特流域管理局表示,该局没有积极参与处理这一问题。这不一定与此前有关协调工作的说法矛盾:参加讨论和负责开展行动并不是一回事。清理工作由郡议会组织;除了这一点,各方报道并未充分说明职责如何划分。⁠1⁠2

目前也没有确定的清理总成本,也没有说明鱼尸被运往何处、以何种方式处置。对居民来说,眼下最直接的未解问题更简单:这种气味还会持续多久。

这一解释有重要局限

郡议会称,这些鱼的死亡是自然发生的事件。该议会的解释是,鲤鱼从科拉克湖进入巴龙加鲁克溪产卵,随后遭遇水流量偏低和氧气不足。低氧仍只是推测中的死因;报道并未提供针对这次事件的氧气读数、采样日期或量化的水流测量数据,以证实这一判断。⁠1

维多利亚州环保署表示,由于鱼类死亡事件不涉及废弃物或污染,该署不会进一步调查。这解释了监管机构作出该决定的原因,却没有补上缺失的测量数据。报道也未证实本地鱼类是否死亡。已确认死亡的数千条鲤鱼,并不能证明受影响的只有鲤鱼。⁠1

这些局限并不意味着清理工作没那么必要。但它们确实关系到我们如何理解事件经过,也有助于避免在原因和完整生态损失尚未得到确证时,声称相关情况已经得到确凿记录。

麦克尼尔回忆称,该地区上一次发生如此大规模的鱼类死亡约在 2009 年。他的回忆只是一个大致的对比,并非经过核实的历史事件排名。他从中得出的教训是,尽管当时人们一度以为鲤鱼已经全部死亡,但它们的数量后来又恢复了。换句话说,壮观的大规模死亡并不等同于对种群数量的长期控制。⁠1

控制仍存活的鱼类

维多利亚渔业管理局休闲渔业经理泰勒·亨特称,鲤鱼是水道中的“棘手难题”。他举出的例子让人得以了解其中的难度:在塔斯马尼亚州的两条水道中,基本根除鲤鱼的工作耗时近 30 年,花费超过 A$15 million。这些数字描述的是塔斯马尼亚州的行动,并非科拉克湖的预算或时间表。⁠1

正在考虑的当地方案包括设置隔网,阻止鲤鱼进入溪流产卵;以及在湖泊自然干涸时大规模捕捞。这两种方案都还不是已经宣布的当地根除计划。吸力卡车正在收集死鱼;这并不意味着已经开始捕捉活鱼。亨特表示,目标是将鲤鱼数量降到不再造成重大影响的水平,即便最终无法将其彻底清除。⁠1

鲤鱼病毒最终可能成为另一种工具,但亨特明确表示,安全且可行是采用该方法的前提条件。他对 ABC 说:“如果这种病毒投入使用,而且是安全可行的选择,我们也会把它纳入工具箱。”澳大利亚联邦科学与工业研究组织(CSIRO)的测试仍在继续,目前尚未宣布获批在科拉克湖使用该病毒。⁠1

维多利亚渔业管理局提供的更广泛信息提到,实验室测试和全国性建模显示,在不同条件下,鲤鱼种群可能减少 30–80 percent。这并非在野外释放后的实证结果,也不是对科拉克湖的预测。它也没有解释目前这次鱼类死亡事件的原因。ABC 于 5 月报道,全国研究预计将持续到 2028 年;这是研究的时间范围,并非承诺的投放日期。⁠15⁠14

任何未来的生物控制手段都会带来尸体处理方面的新问题。科拉克的清理工作展示了这在实际中意味着什么:需要设备、持续清除鱼尸,还要让居民等待异味消退。有关部门尚未宣布何时决定当地的种群控制方案。清除 40 吨鱼尸是一项重大的工作。要防止鱼尸再次堆积,就需要决定如何处理仍然存活的鱼。

来源8

在此处引用的来源中,Colac Herald最先发布,比本报道播出早4天。 随后还有2家媒体发布。

4篇早期文章作为背景资料参阅。5家媒体未注明日期:Court Services Victoriaomny.fmagriculture.gov.aucarpactionalliance.auMirage News

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来自 8 家媒体的 16 个来源· 引用最多的优先

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  1. Crews have vacuumed about forty tonnes of dead carp out of a creek. Residents in Colac are still living with the smell of rotting fish, and the cleanup continues. The longer-term problem is how to stop carp building up in the waterway again.
  2. Colac Otway Shire Council estimates crews have removed forty thousand kilograms from Barongarook Creek in south-west Victoria. That estimate was made public on November sixth. It measures the weight collected so far, with more work still needed.
  3. Long-time resident Pam Cuthbertson described the fish packed together. “Thousands and thousands all jammed up against each other. You couldn't get a twig between them.” She called the situation “an environmental disaster.” For people around the creek, decomposing fish have brought an odour spreading through the surrounding area.
  4. Authorities say carp swam from adjoining Lake Colac into Barongarook Creek to spawn. The council believes low flows left the water short of oxygen during breeding season, killing thousands of fish. It describes the deaths as naturally occurring.
  5. EPA Victoria says it won't investigate further because the deaths didn't involve waste or pollution. The council's low-oxygen explanation remains the suspected cause. Removing carcasses addresses the immediate smell, while managing carp living in the lake requires a longer-term response.
  6. The council warned on October thirtieth that dead carp could continue for weeks, depending on weather and water conditions. A vacuum-pump trial succeeded on November second. Removal ramped up by November fourth, and many carcasses appeared cleared by November fifth.
  7. The council coordinated with EPA Victoria, the state environment department and the Corangamite Catchment Management Authority. Contractors were to remove concentrations of dead carp where practical. The catchment authority later said it had no active management role. That leaves the council running the removal operation, with coordination involving several agencies.
  8. A truck fitted with suction equipment is vacuuming carcasses from the creek. Doug McNeill, the council's infrastructure and environment general manager, says it's been effective at removing fish and reducing the smell. He warns some odour will continue and asks residents for patience.
  9. McNeill recalls the region's last fish kill on this scale around 2009. At the time, some people thought the carp had all died. But numbers recovered. His recollection shows the difficulty facing the current response. Even a large die-off can leave carp able to rebuild their population.
  10. Taylor Hunt, the Victorian Fisheries Authority's recreational fishing manager, says functionally eradicating carp from two Tasmanian waterways took almost thirty years. It cost more than fifteen million Australian dollars. Those figures describe Tasmania's effort, separate from the work facing Lake Colac.
  11. Hunt says authorities are considering screens to block carp entering the creek to spawn. Another possibility is mass catches when the lake naturally dries up. A carp virus could eventually become another tool. For now, crews are collecting dead fish, while those options remain under consideration for controlling the living population.
  12. Hunt makes safety and practicality conditions for using a virus. CSIRO is still testing that option. His immediate aim is to reduce carp numbers enough to limit their impact on waterways, even if eliminating them proves out of reach.
  13. Laboratory testing and national modelling suggest the virus could reduce carp populations substantially, depending on conditions. Scientists still have to work through that research. Any eventual use would also bring the practical challenge of managing dead carp, the same kind of task crews are dealing with now.
  14. The modelled reduction ranges from thirty to eighty percent, depending on conditions. That hasn't been demonstrated through a field release, and it isn't a forecast for Lake Colac. National research is expected to extend into 2028, with any release decision still ahead.
  15. The council hasn't given residents a final cleanup date, and authorities haven't announced when they'll choose local population controls. Preventing another accumulation will require decisions about those measures. Hunt's goal is to bring carp numbers below the level where they have a meaningful impact on the waterways.

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